TY - JOUR. T1 - Asymmetric Synthesis of α,β-Dialkyl-α-phenylalanines via Direct Alkylation of a Chiral Alanine Derivative with Racemic α-Alkylbenzyl Bromides. A Case of High Enantiomer Differentiation at Room Temperature. AU - Soloshonok, Vadim A.. AU - Tang, Xuejun. AU - Hruby, Victor J. AU - Van Meervelt, Luc. PY - 2001/2/8. Y1 - 2001/2/8. N2 - (Matrix Presented) This study demonstrates that the direct alkylation of a Ni(ll)-complex of the chiral Schiff base of alanine with (S)-o-[N-(N-benzylprolyl)amino]-benzophenone, with racemic α-alkylbenzyl bromides, is a synthetically feasible and methodologically advantageous approach to the target α,β-dialkylphenylalanines over previously reported methods. For the first time we report and rationalize a case of a high enantiomer differentiation process at room temperature.. AB - (Matrix Presented) This study demonstrates that the direct alkylation of a Ni(ll)-complex of the chiral Schiff base of alanine with ...
Global Ethyl Bromoacetate Sales Market Report 2018 1 Ethyl Bromoacetate Market Overview 1.1 Product Overview and Scope of Ethyl Bromoacetate 1.2 Classification of Ethyl Bromoacetate by Product Category 1.2.1 Global Ethyl Bromoacetate Market Size (Sales) Comparison by Type (2013-2025) 1.2.2 Global Ethyl Bromoacetate Market Size (Sales) Market Share by Type (Product Category) in 2017 1.2.3 Food Grade 1.2.4 Pharmaceutical Grade 1.3 Global Ethyl Bromoacetate Market by Application/End Users 1.3.1 Global Ethyl Bromoacetate Sales (Volume) and Market Share Comparison by Application (2013-2025) 1.3.2 Chemicals 1.3.3 Pharmaceuticals 1.3.4 Food Industry 1.3.5 Other 1.4 Global Ethyl Bromoacetate Market by Region 1.4.1 Global Ethyl Bromoacetate Market Size (Value) Comparison by Region (2013-2025) 1.4.2 United States Ethyl Bromoacetate Status and Prospect (2013-2025) 1.4.3 China Ethyl Bromoacetate Status and Prospect (2013-2025) 1.4.4 Europe Ethyl Bromoacetate Status and Prospect (2013-2025) 1.4.5 Japan Ethyl ...
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene (or their equivalents).[1] An alkyl group is a piece of a molecule with the general formula CnH2n+1, where n is the integer depicting the number of carbons linked together. For example, a methyl group (n = 1, CH3) is a fragment of a methane molecule (CH4). Alkylating agents use selective alkylation by adding the desired aliphatic carbon chain to the previously chosen starting molecule. This is one of many known chemical syntheses. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline.[2]. In medicine, alkylation of DNA is used in ...
Headline: Bitcoin & Blockchain Searches Exceed Trump! Blockchain Stocks Are Next!. Alkylation Catalysts Market analysis is provided for global market including development trends by regions, competitive analysis of the Alkylation Catalysts market. Alkylation Catalysts Industry report focuses on the major drivers and restraints for the key players. Alkylation Catalysts Market research report also provides granular analysis of the sales, market growth market share, segmentation, revenue forecasts and geographic regions of the market. Alkylation is the transfer of an alkyl group from one molecule to another. Alkylation of isobutane with olefins in the petroleum is an important industrial process to improve the octane number. As the most usually liquid acid catalysts, concentrated sulfuric acid (H2SO4) and hydrofluoric acid (HF) have potential environmental problem especially for the HF alkylation process.. Browse Detailed TOC, Tables, Figures, Charts and Companies Mentioned in Alkylation Catalysts ...
Here, we demonstrate that OTUD4 may serve as a master regulator of alkylation damage resistance through stabilization of the human AlkB homologues. A number of distinct lines of evidence support this role for OTUD4. First, OTUD4 interacts specifically with ALKBH2 and ALKBH3 and encodes a K48‐specific DUB (Fig 1). Consistently, ALKBH3 is subjected to K48‐linked ubiquitination and proteasomal degradation (Fig 2A-D). OTUD4 antagonizes ALKBH3 ubiquitination and stabilizes both ALKBH2 and ALKBH3 in vivo (Fig 2E-H). ALKBH3 protein levels do not correlate well with ALKBH3 mRNA levels in various tumor cell lines but do correlate with OTUD4 levels (Supplementary Fig S2). Finally, overexpression of ALKBH3 in PC‐3 cells, which depend primarily on ALKBH3 instead of ALKBH2 for alkylation damage resistance, is sufficient to rescue alkylation damage sensitivity upon loss of OTUD4 (Fig 7G).. What is most striking is that we find OTUD4 catalytic activity to be apparently dispensable for its stabilization ...
DNA repair of alkylation damage is defective in various cancers. This occurs through somatically acquired inactivation of the MGMT gene in various cancer types, including breast cancers. In addition to MGMT, the two E. coli AlkB homologs ALKBH2 and ALKBH3 have also been linked to direct reversal of alkylation damage. However, it is currently unknown whether ALKBH2 or ALKBH3 are found inactivated in cancer. Methylome datasets (GSE52865, GSE20713, GSE69914), available through Omnibus, were used to determine whether ALKBH2 or ALKBH3 are found inactivated by CpG promoter methylation. TCGA dataset enabled us to then assess the impact of CpG promoter methylation on mRNA expression for both ALKBH2 and ALKBH3. DNA methylation analysis for the ALKBH3 promoter region was carried out by pyrosequencing (PyroMark Q24) in 265 primary breast tumours and 30 proximal normal breast tissue samples along with 8 breast-derived cell lines. ALKBH3 mRNA and protein expression were analysed in cell lines using RT-PCR and
Tang, X.; Soloshonok, V.A.; Hruby, V.J., 2001: Asymmetric synthesis of alpha,beta-disubstituted-alpha-amino acids via direct alkylation of chiral amino acid derivatives with racemic sec-alkyl bromides
Chelated enolates are versatile nucleophiles for palladium-catalysed allylic alkylations. Even with complex allylic substrates the reaction proceed without significant isomerisation. This allows the stereoselective introduction of polyhydroxylated allylic sidechains into amino acids and peptides with retention of the olefin geometry ...
The value derived for Henrys Law constant H relates to the properties of the substance oligomerisation and alkylation reaction products of 2-phenylpropene and phenol [EC no. 700-960-7]. Vapour pressure (VP) and water solubility (WS) were obtained from tests with different samples of the substance (see CSR Chapter 1.3). The molecular weight was determined as average molecular weight of the different commercial products of the substance taking into account the percentage of the components in the products and their respective molecular weights. The 90th percentile of these data was taken as characteristic average molecular weight for the substance (average MW 298 g/mol). The constant H for the substance oligomerisation and reaction product … is calculated using the vapour pressure of 0.044 Pa and the water solubility of 4 mg C/L (= 0.0134 mol/m³), both at 21°C (see Chapter 1.3.). Dimension of H is Pa*m³/mol. H = VP / WS x MW = 0.044 Pa / 4 mg/L x 298 g/mol = 3.278 Pa*m³/mol ...
Isobutene/olefin alkylation is a major refinery process in which light hydrocarbons (isobutene and, mainly, C3 and C4 olefins) are converted to a high octane gasoline feedstock. Alkylate currently accounts for a key fraction of the total U.S. gasoline pool; in fact, concerns over emissions have led to an interest in increasing the amount of alkylate used in gasoline. However, environmental and safety concerns present a barrier to this increase, as current processes for alkylate production employ hazardous liquid acids. As yet, a practical process based on solid catalysts has not been identified ¿ conventional fixed bed processes have faced rapid catalyst aging and downtime for regeneration. This project will develop a novel reactor approach to solid-catalyzed isobutene/olefin alkylation in which olefin polymerization at the catalytic surface is limited, thereby avoiding the primary issue with solid catalyzed alkylation. Moreover, the proposed approach offers the potential for higher quality ...
TY - JOUR. T1 - Direct and stereoselective synthesis of β-mannosides by anomeric o-alkylation. AU - Takahashi, Daisuke. PY - 2016. Y1 - 2016. KW - Anomeric O-alkylation. KW - Glycosylation. KW - Stereoselective. KW - β-mannosylation. UR - http://www.scopus.com/inward/record.url?scp=84997542885&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=84997542885&partnerID=8YFLogxK. U2 - 10.4052/tigg.1608.6E. DO - 10.4052/tigg.1608.6E. M3 - Comment/debate. AN - SCOPUS:84997542885. VL - 28. SP - E119-E120. JO - Trends in Glycoscience and Glycotechnology. JF - Trends in Glycoscience and Glycotechnology. SN - 0915-7352. IS - 164. ER - ...
This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions.. The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. An OH-Pd hydrogen bond in Pd(0)-π-olefin complexes of hydroxy-containing oxazoline ligands was identified by density functional theory computations and helped to rationalize the contrasting results obtained employing hydroxy- and methoxy-containing ligands in the catalytic reaction. This type of hydrogen bond was further studied in phenanthroline metal complexes. As expected for a hydrogen bond, the strength of the bond was found to increase with increased electron density at the metal and with increased acidity of the hydroxy protons.. The second part deals with the use of hydroxy- and methoxy-containing phosphinooxazoline ligands in the rhodium- and iridium-catalyzed asymmetric hydrosilylation reaction. The ...
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1.1. Organolithium and Grignard reagents as nucleophiles - Metalation of halogenated compounds - Hydrogen/metal exchange - Halogen/metal exchange - General reactivity of electrophiles - Reaction of Organolithium and Grignard reagents - Diastereoselectivity of nucleophilic addition (Felkin-Anh, Cram - Enantioselectivity of organozinc/aldehyde additions 1.2. Reaction with organocopper reagents 1. Dithianes 2. O-Alkylated cyanohydranes 3. Alpha lithiated vinyl ethers 1.4. Homoenolate equivalents 1.5. Olefination of carbonyl compounds 1. Wittig reaction (Unstabilized ylides) 2. Horner-Emmons modification (stabilized ylides) 3. C.W. Still Modification 4. Peterson reaction 5. Methylenation of carbonyl compounds by Tebbe reagent 1. Reaction with saturated aldehydes and ketones 2. Reaction with α, β-unsaturated ketones 1. Preparation of enolates by α-deprotonation 2. Alkylation - Alkylation of enolates derived from 1,3-dicarbonyl compounds - Alkylation at γ position of 1,3-dicarbonyl compounds - ...
1993) have been devel- oped as generic reagents for introducing fluorine-18 into N-isopropyl groups by the reductive alkylation augmentin sf syrup direct alkylation of secondary amines, FAF488 appears to be augmetnin distributed and shows focally reduced intensity.
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TY - JOUR. T1 - Sulfhydryl Site-Specific Cross-Linking and Labeling of Monoclonal Antibodies by a Fluorescent Equilibrium Transfer Alkylation Cross-Link Reagent. AU - del Rosario, Renato B.. AU - Wahl, Richard L.. AU - Brocchini, Stephen J.. AU - Lawton, Richard G.. AU - Smith, Richard H.. PY - 1990/1/1. Y1 - 1990/1/1. N2 - The site-specific intramolecular cross-linking of sulfhydryls of monoclonal antibodies via a new class of "equilibrium transfer alkylation cross-link (ETAC) reagents" is described. Following complete or partial reduction of interchain disulfides with dithiothreitol (DTT), two murine IgG2a monoclonal antibodies, 225.28S and 5G6.4, were reacted with a,a-bis[(p-tolylsulfonyl)methyl]-m-aminoacetophenone (ETAC 1a) and a fluorescent conjugated derivative, sulforhodamine B m-(α,α-bis(p-tolylsulfonylmethyl) acetyl)anilide derivative (ETAC 1b). Reducing SDS-polyacrylamide gel electrophoresis analysis of the products from lb indicated the formation of S-ETAC-S interchain heavy and ...
D4337 - 89(2017) Standard Test Methods for Analysis of Linear Detergent Alkylates , linear alkylbenzenes, linear detergent alkylates ,,
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Visible-light-induced photoredox decarbonylative C-C bond formation with aldehydes is described for the first time. Minisci-type alkylation reactions of N-heteroarenes proceed smoothly at ambient temperature with air as the sole oxidant. The present sustainable protocol uses readily available organofluorescein as a
Description: Subject matter wherein the hydrocarbon feed is treated prior to the alkylation reaction, e.g., by separating nonhydrocarbon therefrom, by separating the feed into several different fractions, etc ...
However, the simplest synthetic approach to the N-9 substituted guanine compounds involves the direct alkylation of appropriately substituted 2-aminopurines e.g. guanine derivatives. There are significant drawbacks to this approach as it always results in a mixture of N-9 and N-7 alkylation products. The undesirable N-7 isomers are produced in large amounts, which in turn necessitate tedious and in-efficient methods of separation such as silica gel chromatography in order to obtain the desired N-9 isomer at a favourable degree of purity. Use of halogenated purines can. hardly be selected as methods for industrial production, as their starting materials are expensive and difficult to acquire, and they demand a reaction with ammonia at high temperature and pressure in order to obtain guanine nucleosides, such as acyclovir, ganciclovir etc. Hence, it is highly desirable to develop a regioscpecific process for the manufacture of ganciclovir ...
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice ...
S-Adenosyl-L-Methionine (a.k.a., SAM, AdoMet) is a cofactor that is crucial to many biological processes. Specifically, SAM is a cationic sulfur-based alkylatin...
see article for more reactions. Abstract. A Cp*Ir complex bearing a functional bipyridonate ligand is a highly effective and versatile catalyst for the α-alkylation of ketones with primary alcohols under environmentally benign and mild conditions. Furthermore, this complex also exhibited a high level of catalytic activity for the α-methylation of ketones with methanol.. ...
Press release - Market Research Hub - Global Alkylation Catalyst Market Analysis By Application 2025 | Top Key Players Albemarle, BASF, CRI, Sinopec - published on openPR.com
sensitive.. Recommended solvents are DMSO or CHCl3 with or without H2O/TFA (0.1 ml of TFA in 2 ml of water). H2O/TFA can change the regioselectivity and conversion of the reaction.. Prepare a solution of ...
Starting from N-methyl-1-{(3S,4S)-4-[2-(trifluoromethyl)phenoxy]-3,4-dihydro-1H-isochromen-3-yl}methanamine (1) target compound 2 is prepared using a mild, direct alkylation approach with 2-fluoroethyl trifluoromethanesulfonate.
In this video Ill teach you why alpha-hydrogens are so acidic, and how we can use that property to do some cool organic reactions. Ill talk about keto-enol tautomerism, LDA (lithium diisopropyl amine), alpha-halogenation, alkylation, acylation, beta-alkylation, the aldol reaction, the Claisen condensation, the Robinson annulation, decarboxylation, and the malonic ester synthesis. --Dr. Mike Christiansen from Utah State University
Were found to alkylate all oxygens and nitrogens in nucleic acids , whereas a host of more moderately reactive electrophilic agents typically target nitrogens
Literature References: Antitumor antibiotic; alkylates DNA by interstrand crosslinking of the major groove. Isoln from Streptomyces sahachiroi: T. Hata et al., J. Antibiot. 7A, 107 (1954). Purification: H. Kamada et al., ibid. 8A, 187 (1955). Mechanism of action: J. W. Lown, K. C. Majumdar, Can. J. Biochem. 55, 630 (1977); T. Fujiwara, I. Saito, Tetrahedron Lett. 40, 315 (1999). Proposed structure: J. W. Lown, C. C. Hanstock, J. Am. Chem. Soc. 104, 3213 (1982). Identity with azinomycin B: E. J. Moran, R. W. Armstrong, Tetrahedron Lett. 32, 3807 (1991). Purification: K. Nagaoka et al., J. Antibiot. 39, 1527 (1986). Total structure as azinomycin B: K. Yokoi et al., Chem. Pharm. Bull. 34, 4554 (1986). ...
Digitization process: Scanned using an Epson 750 as 1200 ppi, 48-bit, RGB, .tif; service master changed to black and white, levels and contrast adjusted, sharpened and cropped; derivative resampled to 3000 pixels on the long edge, 24-bit .jpg ...
T. Mathew, S. Shylesh, S. N. Reddy, S. C. Peter, S. K. Date, B. S. Rao and S. D. Kulkarni, Redistribution of cations amongst different lattice sites in Cu1-xCoxFe2O4 ferrospinels during alkylation: magnetic study. , Cat. Lett. 93, 155 - 160 (2004 ...
An enantioselective synthesis of allenes through palladium-catalyzed asymmetric allylic alkylation using a chiral diaminophosphine oxide is described. The asymmetric allylic alkylations proceeded in the presence of a catalytic amount of lithium acetate at 4 °C, affording the chiral allenes in excellent yield with up to 99% ee. ...
Involvement of two endonuclease III homologs in the base excision repair pathway for the processing of DNA alkylation damage in Saccharomyces cerevisiae.
Dottavio-Martin, D.; Ravel, J.M., 1978: Radiolabeling of proteins by reductive alkylation with [14C]formaldehyde and sodium cyanoborohydride
Looking for online definition of ethylated in the Medical Dictionary? ethylated explanation free. What is ethylated? Meaning of ethylated medical term. What does ethylated mean?
Summary of Facts and Submissions. I. The appeal is from the decision of the Opposition Division to maintain the European patent 1 138 750 in amended form.. II. In opposition procedure the Opponent raised inter alia objections with regard to sufficiency of disclosure, lack of novelty and lack of inventive step and cited among others documents. D6: US-A-5 648 586. D7: STRATCO, The 1990 Alkylation Seminar:. J.-L. Nocca, C5s Selective Hydrogenation and Etherification. D8: STRATCO, The 1990 Alkylation Seminar: K. Masters, Amylene Alkylation. D9: NPRA Q&A Sessions: C5 alkylation questions (from 1989 to 1993). D17: STRATCO, The 1990 Alkylation Seminar:. J.-L. Nocca, Etherification. D18: STRATCO, The 1990 Alkylation Seminar:. J.-L. Nocca, Upgrading Alkylation Feedstocks by Hydrogenation. D21: WO-A-97/03148. III. In its decision the Opposition Division concluded inter alia that the Opponent was not allowed to start argumentation for the first time from a combination of documents D7,D17 and D18 at a very ...
The feasibility of distilling alkylation product and technical alkyl phenol in a continuous apparatus was established. The conditions for distilling the alkylation product and technical alkyl phenol was determined. In terms of its preliminary performance characteristics (sedimentation and increase in viscosity), additive BFK prepared on the basis of the target alkyl phenol distilled in the continuous apparatus surpasses the additive prepared on the basis of technical alkyl phenol with the periodic apparatus.(*DISTILLATION
TY - GEN. T1 - Modeling of benzene with ethylene alkylation. AU - Khlebnikova, Elena. AU - Dolganova, Irena. AU - Ivashkina, Elena. AU - Koshkin, Stanislav. PY - 2016/4/19. Y1 - 2016/4/19. N2 - The paper considers the benzene alkylation with ethylene model development with the use of zeolite catalyst. A list of reactions occurring in the alkylation reactor was made and the thermodynamic possibility of determination of these reactions by the change of Gibbs energy was defined. The paper presents the hydrocarbons transformation scheme, which includes the grouping of components on the basis of their reactivity and the degrees of compensation values of the corresponding reactions. Drawing on the obtained data the authors developed the kinetic model of the alkylation of benzene with ethylene.. AB - The paper considers the benzene alkylation with ethylene model development with the use of zeolite catalyst. A list of reactions occurring in the alkylation reactor was made and the thermodynamic ...
The first direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.. ...
Alkylation reactions represent an important organic transformation to form C-C bonds. In addition to conventional approaches with alkyl halides or sulfonates as alkylating agents, the use of unactivated olefins for alkylations has become attractive from both cost and sustainability viewpoints. This Review summarizes transition-metal-catalyzed alkylations of various
0019] In other embodiments the adjusting is done by changing a ratio of isoparaffin to olefin in a feed to the alkylation reactor. In general, lowering the molar ratio of isoparaffin to olefin in the feed will produce a higher level of C5+ hydrocarbons in the process unit that boil above 280° F. (137.8 degree Celsius). In one embodiment, the molar ratio of isoparaffin to olefin in the feed while operating the alkylation reactor in the alkylate mode is from 4:1 to 100:1, such as from 4:1 to 50:1, or from 4:1 to 20:1; and the molar ratio of isoparaffin to olefin in the feed while operating the alkylation reactor in the distillate mode is a lower molar ratio from that used during the alkylate mode, from 0.25:1 to 25:1, such as from 0.25:1 to 20:1, or 0.25:1 to 10:1. In a different embodiment the molar ratio of isoparaffin to olefin in the feed is approximately the same while operating in both the alkylate mode and the distillate mode. In one embodiment, the control system connected to the ...
Looking for online definition of alkylate in the Medical Dictionary? alkylate explanation free. What is alkylate? Meaning of alkylate medical term. What does alkylate mean?
TY - JOUR. T1 - Thermodynamic analysis of benzene alkylation with propylene. AU - Chudinova, Alena A.. AU - Nurmakanova, Asem E.. AU - Salishcheva, Anastasiya A.. AU - Ivashkina, Elena N.. PY - 2015. Y1 - 2015. N2 - Relevance of the research is caused by broad application of alkylation in industry and the necessity to develop a mathematical model adequate on the predicting ability and suitable for solving the technological problems in producing cumene with aluminum chloride. The main aim of the research is to define and to study the thermodynamic and kinetic regularities of benzene alkylation with propylene in the presence of aluminum chloride applying the methods of quantum chemistry. The methods used in the study: electronic-structural method based on density functional theory (DFT, DFT) at B3LYP. Search for transition state of the reaction in the presence of Lewis acids was performed by QST2 at B3LYP / 631 ++ G(d,p) and LSDA / 631 ++ G(d,p). The results. The thermodynamic parameters of the ...
Alkyltransferase-like proteins (ATLs) share functional motifs with the cancer chemotherapy target O(6)-alkylguanine-DNA alkyltransferase (AGT) and paradoxically protect cells from the biological effects of DNA alkylation damage, despite lacking the reactive cysteine and alkyltransferase activity of AGT. Here we determine Schizosaccharomyces pombe ATL structures without and with damaged DNA containing the endogenous lesion O(6)-methylguanine or cigarette-smoke-derived O(6)-4-(3-pyridyl)-4-oxobutylguanine. These results reveal non-enzymatic DNA nucleotide flipping plus increased DNA distortion and binding pocket size compared to AGT. Our analysis of lesion-binding site conservation identifies new ATLs in sea anemone and ancestral archaea, indicating that ATL interactions are ancestral to present-day repair pathways in all domains of life. Genetic connections to mammalian XPG (also known as ERCC5) and ERCC1 in S. pombe homologues Rad13 and Swi10 and biochemical interactions with Escherichia coli ...
TY - JOUR. T1 - In vivo DNA alkylation and somatic cell mutation in Drosophila.(共著). AU - Negishi, Tomoe. PY - 1992. Y1 - 1992. M3 - Article. VL - 272. SP - 275. EP - 275. JO - Mutation Res.. JF - Mutation Res.. ER - ...
Expression of the Escherichia coli aidB gene is induced in vivo by alkylation damage in an ada-dependent pathway and by anaerobiosis or by acetate at pH 6.5 in an ada-independent fashion. In this report, we present data on aidB gene structure, function, and regulation. The aidB gene encodes a protein of ca. 60 kDa that is homologous to several mammalian acyl coenzyme A dehydrogenases. Accordingly, crude extracts from an aidB-overexpressing strain showed isovaleryl coenzyme A dehydrogenase activity. aidB overexpression also reduced N-methyl-N-nitro-N-nitrosoguanidine-induced mutagenesis. Both ada- and acetate/pH-dependent induction of aidB are regulated at the transcriptional level, and the same transcriptional start point is used for both kinds of induction. Ada protein plays a direct role in aidB regulation: methylated Ada is able to bind to the aidB promoter region and to activate transcription from aidB in an in vitro transcription-translation system using crude E. coli extracts.
Using in situ solid-state NMR spectroscopy we show that CO can act as an alkylating reagent and react with benzene to produce toluene over a Zn/H-ZSM-5 zeolite. In the alkylation reaction, CO provides the methyl group of toluene via a methoxy intermediate.
The first part of this thesis addresses the design and synthesis of amine building blocks accomplished by applying two different synthetic procedures, both of which were developed using solid-phase chemistry. Chapter 1 presents the first of these methods, entailing a practical solid-phase parallel synthesis route to N-monoalkylated aminopiperidines and aminopyrrolidines achieved by selective reductive alkylation of primary and/or secondary amines. Solid-phase NMR spectroscopy was used to monitor the reactions for which a new pulse sequence was developed. The second method, reported in Chapter 2, involves a novel approach to the synthesis of secondary amines starting from reactive alkyl halides and azides. The convenient solid-phase protocol that was devised made use of the Staudinger reaction in order to accomplish highly efficient alkylations of N-alkyl phosphimines or N-aryl phosphimines with reactive alkyl halides.. The second part of the thesis describes the design and synthesis of three ...
Epichlorohydrin (ECH) is a DNA bifunctional alkylating agent that has been shown to form DNA inter-strand cross-links in vitro at the N7 position of guanines at the 5-GNC and 5-GC consensus sequences. We used the quantitative polymerase chain reaction (QPCR) to monitor the formation of in vivo ECH lesions in 6C2 chicken erythroid progerutor cells. Three distinct loci were investigated in order to determine the effect of ECH reactivity in different levels of chromatin condensation. The sites consisted of an open locus of the nuclear genome, a closed locus of the nuclear genome, and a naked locus of the mitochondrial genome. We found that ECH alkylation was preferentially targeted towards the nuclear sites and that chromatin structure had no effect upon ECH reactivity. Repair assays of the three sites revealed that there appears to be no repair of ECH lesions in the nuclear genome.
Biosketch. B.Sc. Biochemistry, Aberdeen University, Scotland 1974 Ph.D. Molecular Biology, Imperial Cancer Research Fund and University College, London University, England 1978 Director, MIT Center for Environmental Health Sciences, MIT, 2001 Affiliate, MIT Center for Cancer Research, 2001 Adjunct Professor of Toxicology, Harvard School of Public Health, 2001 Executive Committee, MIT Computational and Systems Biology Initiative (CSBi). Research Summary. Research in the Samson lab is aimed at understanding how cell, tissues, animals and ultimately people respond upon exposure to environmental toxicants in general, and alkylating agents in particular. A wide variety of DNA repair pathways provide protection against DNA alkylation damage and it is now clear that a multitude of other pathways are important for cellular recovery. Our goal is to understand how these pathways function, how they are regulated, and how they integrate to determine the ultimate biological and health consequences of ...
... Alkylating the Nitrogen of a peptide bond is one modern approach to equip peptide based biopharmaceuticals with proteolytic stability and altered activity. They can be synthesized in a repetitive manner, just as peptides by
To investigate the mechanism of cell death induced by the N-alkylated prodigiosin analogue, 2,2′-[3-methoxy-1′amyl-5′-methyl-4-(1′′-pyrryl)] dipyrryl-methene (MAMPDM) in S-180 and EL-4 tumour cell lines. Effect of MAMPDM on cell viability was assessed by MTT dye conversion. Induction of apoptosis was assessed by monitoring caspase 3 activity using a fluorogenic substrate, fragmentation of DNA by gel electrophoresis and sub-diploid DNA containing cells by flowcytometry. Necrosis was estimated by flowcytometric analysis of the uptake of propidium iodide. MAMPDM inhibited the proliferation of murine fibrosarcoma, S-180 cells and induced cell death. Investigations into the mechanism of cell death by MAMPDM in S-180 cells showed absence of hallmarks of apoptotic cell death such as activation of caspase 3, DNA fragmentation and presence of cells with sub-diploid DNA content. However, there was a rapid loss of membrane integrity as assessed by uptake of propidium iodide, which is characteristic of
Repeated dose toxicity information is available from an oral sub-chronic toxicity study (OECD 408 - Repeated Dose 90-day Oral Toxicity Study in Rodents, see below). For inhalation exposure, route-to-route extrapolation is applied. The dose descriptor starting point is converted into the modified dose descriptor starting point using the following equation (see Guidance IR&CSA Chapter R.8, Figure R. 8-3, p 21): correctedinhalatory NOAEC = oral NOAEL x 1 / 0.38 (m³ / kg / d) x (Absoral-rat /Absinh-human) x 6.7 m³ (RV: 8h, standard) / 10 m³ (RV: 8h, light work) = 40 x 1/0.38 x 0.5/1 x 6.7/10 = 35.26 mg/m³ ...
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Deamination Chemistry: Nucleic Acid Alkylation & Cross-Linking. We have been interested in two types of deaminations and their relation to modifications of DNA bases. The first type relates to the deamination of amines (and derivatives) and their role in the alkylation of DNA. The other relates to the deamination of amino groups in DNA bases. Both of these processes have important biological consequences. In this context, we have been studying decomposition pathways from the bottom up beginning with diazonium ions. We proposed a new bonding model and established crucial links between theory and experiment. Current studies of diazonium ions focus on the mechanisms of their SN chemistry and studies of the diazonium ions of DNA bases. To address questions as to the consequences of alkylation on DNA and RNA structure and properties, our initial studies have focused on studies of base pairing. Non-Synergistic Bonding & Thymine Dimerization. Our analysis of H-bonded Adenine-Thymine, A=T, suggests ...
Alkylating agents exert a wide range of biological effects in both pro- and eukaryotes and there is ever increasing evidence that these effects are mediated via alkylation at the O6position of...
An efficient catalytic system for the alkylation of amines with either alcohols or amines under mild conditions has been developed, using cyclometallated iridium complexes as catalysts. The method has broad substrate scope, allowing for the synthesis of a diverse range of secondary and tertiary amines with good to excellent yields. By controlling the ratio of substrates, both mono- and bis-alkylated amines can be obtained with high selectivity. In particular, methanol can be used as the alkylating reagent, affording N-methylated products selectively. A strong solvent effect is observed for the reaction.
Sodium triacetoxyborohydride has emerged as one of the reagents used most frequently for carrying out reductive amination of carbonyl compounds, a reaction that is also known as reductive alkylation of amines. A disadvantage of sodium triacetoxyborohydride is its poor solubility, and that product isolation requires an aqueous quench followed by liquid-liquid extraction and column chromatography.. Biotage® MP-Triacetoxyborohydride was developed to perform in a manner similar to that of sodium triacetoxyborohydride, while simplifying reagent handling and product purification. Moreover, for many of these reactions, a scavenger resin may be added for one-pot purification of the product.. ...
Xiao J,KaiZhao,TeckPengLoh. Highly Enantioselective Intermolecular Alkylation of Aldehydes with Alcohols by Cooperative Catalysis of Diarylprolinol Silyl Ether with Brønsted Acid[J]. Chemistry-An Asian Journal,2011,6:2890 ...
The elucidation of signalling pathways relies heavily upon the identification of protein kinase substrates. Recent investigations have demonstrated the efficacy of chemical genetics using ATP analogues and modified protein kinases for specific substrate labelling. Here we combine N(6) -(cyclohexyl)ATPγS with an analogue-sensitive cdk2 variant to thiophosphorylate its substrates and demonstrate a pH-dependent, chemoselective, one-step alkylation to facilitate the detection or isolation of thiophosphorylated peptides.
Nayfeh, S and Dowden, E, "Effects of alkylation of rna synthesis by ehrlich ascites tumors in vivo. Abstr." (1969). Subject Strain Bibliography 1969. 982 ...
Reports emphasize developments in process technology for Alkylation for Motor Fuels that have potential implications for the chemical and energy industries
Alkylation, in petroleum refining, chemical process in which light, gaseous hydrocarbons are combined to produce high-octane components of gasoline. The light hydrocarbons consist of olefins such as propylene and butylene and isoparaffins such as isobutane. These compounds are fed into a reactor,
ALKBH2 - ALKBH2 (Myc-DDK-tagged)-Human alkB, alkylation repair homolog 2 (E. coli) (ALKBH2), transcript variant 3 available for purchase from OriGene - Your Gene Company.
Preview - Issue 42/2006 Angewandte Chemie Highlights Asymmetric Synthesis Tsuji-Trost Allylic Alkylation with Ketone Enolates M. Braun and T. Meier An FeVI Nitride: There Is Plenty of Room at the Top! High Oxidation States P. J. Chirik 1 Reviews Green Chemistry 1 Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process J. L. G. Fierro et al. Communications Microporous Materials 2 F. P. Gabba0 et al. Molecular Recognition 3 F. W. Scheller et al. Oxidative C C Coupling 4 Hydrocarbon Uptake in the Alkylated Micropores of a Columnar Supramolecular Solid (Cover Picture) 2 A Bifunctional Molecularly Imprinted Polymer (MIP): Analysis of Binding and Catalysis by a Thermistor Intermolecular Oxidative Enolate Heterocoupling P. S. Baran and M. P. DeMartino Antibiotics Total Synthesis of Platensimycin 3 K. C. Nicolaou et al. Heterogeneous Catalysis S. L. Buchwald et al. Domino Cu-Catalyzed C N Coupling/ Hydroamidation: A Highly Efficient Synthesis of Nitrogen Heterocycles Natural Products ...
Several of the pathways of metabolism of the suspected carcinogen acrylonitrile (AN) were identified previously in this laboratory with the use of subcellular fractions and purified enzymes (Guengerich, F. P., Geiger, L. E., Hogy, L. L., and Wright, P. L., Cancer Res., 41: 4925-4933, 1981). In order to establish the relative contributions of the various pathways leading to activated and detoxicated products, we examined AN metabolism in isolated Fischer 344 rat hepatocytes as a model. Reduced glutathione (GSH) was depleted, and cell viability was lost in an AN concentration-dependent manner. The major GSH adduct formed at all AN concentrations was identified as S-(2-cyanoethyl)GSH using thin-layer and high-performance liquid chromatography. Acid hydrolysis and amino acid analysis of labeled hepatocellular protein revealed S-(2-carboxyethyl)-cysteine as the major adduct formed, indicating direct alkylation of cysteinyl residues by AN. 2-Cyanoethylene oxide accumulated in the hepatocyte ...
formula I or ketoamide intermediates to prepare compounds of formula I is to to add 1- 20 equivalents but most preferably 5 equivalents of a commercially available solution of 32% peracetic acid in dilute aq acetic acid to the reaction flask containing the completed reaction described in Step A. The reaction is typically stirred at the same temperature at which the alkylation reaction was conducted (for the Step A reactions with an acid chloride in THF -78° and for the step A reactions in DMF ~ -42°) for a period of Ih and then allowed to warm to ambient temperature if not already at that tmeperature. The reaction mixture is then either allowed to react further or immediately diluted with saturated aq. ammonium chloride and EtOAc. For relatively insoluble acid products which precipatate, the resultant precipitate is isolated by filtration as the oxoacetyl product ZC(O)C(O)Y. For organic soluble acid products, the acid is extracted into the organic layer and the layers separated. The organic ...
Steroids: Nilevar a ethylated version of nortestosterone. is the C-17 alpha ethylated derivative of nortestosterone (nandrolone). This modification renders
1D86: Structural consequences of a carcinogenic alkylation lesion on DNA: effect of O6-ethylguanine on the molecular structure of the d(CGC[e6G]AATTCGCG)-netropsin complex.
Tubes have been incubated thirty min at 37 C during the dark. Then 1 uL of 500 mM DTT was Epothilone added to quench the alkylation response. Upcoming four. five uL of 200 mM CaCl2 were added to just about every tube. An extra five uL of 500 mM Tris HCl had been additional to sustain the pH and ionic strength. Ultimately, ten ug of trypsin or chymotrypsin dissolved in one mM HCl had been additional to every single tube. Tubes had been incubated 24 h at 37 C after which frozen at 30 C until eventually preparation for mass spectrometry. Digestion of venoms with Glu C Reduction and alkylation of venoms were carried out as described over, except that as opposed to 500 mM Tris HCl, 167 mM phosphoric acid NaOH was applied. Additionally, the enzyme was dissolved in ultrapure water, as opposed to in one mM HCl. This enabled the enzyme to cleave proteins adjacent to aspartic acid residues, likewise as glutamate residues. Once the enzyme was dissolved in one mM HCl, it cleaved subsequent to glutamate ...
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IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing.<. GHS Signal Word: Warning. EINECSNumber : 226-133-6. Recommended Storage : Refrigerator +4°C. ...
PdCl2 in the presence of dppe or Xantphos(t-Bu) as the ligand is found to be an efficient catalyst for the N-alkylation of various primary and cyclic secondary ...
2) M. Sriram, van der G. A. Marel, H. L. Roelen, van J. H. Boo and A. H. Wang, Structural Consequences of a Carcinogenic Alkylation Lesion on DNA: Effect of O6-ethylguanine on the Molecular Structure of the d(CGC[e6G]AATTCGCG)-netropsin Complex, Biochemistry, 1992, 31(47), 11823. ...
The benzoacronycine derivative, S23906-1, was character-ized recently as a novel potent antitumor agent through alkylation of theN2 positionof guanines inDNA.We show here that its reactivity towards DNA can be modulated by glutathione (GSH). The formation of covalent adducts between GSH and S23906-1 was evidenced by EI-MS, and the use of different GSH derivatives, amino acids and dipeptides revealed that the cysteine thiol group is absolutely required for complex formation because glutathione disul-fide (GSSG) and other S-blocked derivatives failed to react covalently with S23906-1. ... ...
SWISS-MODEL Template Library (SMTL) entry for 3kuy.1. DNA Stretching in the Nucleosome Facilitates Alkylation by an Intercalating Antitumor Agent
A 1-H-pyrazolo-[1,5-b]-1,2,4-triazole having a combination of an arylthio coupling-off group and a tertiary alkyl group attached via its tertiary carbon atom in the 6-position preferably has the general formula: ##STR1## wherein R.sup.1 is a tertiary alkyl group,R.sup.2 is an alkyl or substituted alkyl group, andX is a thioaryl or substituted thioaryl group.
There is also a mention that the more stable the intermediate ion(that is the tertiary carbocation in this case) is, the better the reactivity(means the faster it reacts). Im confused how is it that a more stable compound can be more reactive ...
centanamycin: a potent antimalarial and transmission-blocking DNA-binding agent inspired from ( )-duocarmycin SA that lacks a stereocenter; structure in first source
The alkylation of bromobenzene and toluene on zeolite H-USY (Si/Al 15) was studied using a high-throughput frontal analysis experimental setup. Adsorption properties of the involved components were determined using the batch technique. Reactions were performed using allyl alcohol, allyl acetate, 1-octen-3-ol, and allyl chloride as alkylating agents at 200 degrees C in the liquid phase. The reaction products could be divided into 3 fractions: (1) light components formed in side reactions of the alkylating agent; (2) primary alkylation products resulting from the alkylation of bromobenzene or toluene and subsequent rearrangement reactions; and (3) a heavy fraction consisting of secondary alkylation products and polyaromatics. Whereas the use of allyl chloride and 1-octen-3-ol as alkylating agents resulted mainly in the formation of undesired side products, bromobenzene was efficiently alkylated with allyl alcohol and allyl acetate, resulting in the formation of allyl bromobenzene, cis-2-propenyl ...
We investigated sequence-specific DNA alkylation using conjugates between the N-methylpyrrole (Py)-N-methylimidazole (Im) polyamide and the DNA alkylating agent, chlorambucil, or 1-(chloromethyl)-5-hydroxy-1, 2-dihydro-3H-benz[e]indole (seco-CBI). Polyamide-chlorambucil conjugates 1-4 differed in the position at which the DNA alkylating chlorambucil moiety was bound to the Py-Im polyamide. High-resolution denaturing polyacrylamide gel electrophoresis (PAGE) revealed that chlorambucil conjugates 1-4 alkylated DNA at the sequences recognized by the Py-Im polyamide core moiety. Reactivity and sequence specificity were greatly affected by the conjugation position, which reflects the geometry of the alkylating agent in the DNA minor groove. Polyamide-seco-CBI conjugate 5 was synthesized to compare the efficacy of chlorambucil with that of seco-CBI as an alkylating moiety for Py-Im polyamides. Denaturing PAGE analysis revealed that DNA alkylation activity of polyamide-seco-CBI conjugate 5 was similar ...
Alkylating agents induce cytotoxic DNA base-adducts. In this thesis I provide evidence to suggest that Saccharomyces cerevisiae Tpa1 protein is involved in DNA alkylation repair. Little is known about Tpa1 as a repair protein beyond the initial observation from a high throughput analysis indicating that deletion of TPA1 causes methyl methane sulfonate (MMS) sensitivity in Saccharomyces cerevisiae. Using purified Tpa1, I demonstrate that wild type Tpa1 repairs both single and double-stranded methylated DNA and mutation of the amino acid residues involved in cofactor binding abolishes Tpa1 DNA repair activity. In this thesis I also investigate genetic interaction of Tpa1. I also demonstrate that Tpa1 could complement alkB function and rescue the MMS sensitivity of alkB deficient E.coli strain, HK82. Experimental data proves that deletion of TPA1 along with base excision repair (BER) pathway DNA glycosylase MAG1 renders the tpa1 ∆ mag1 ∆ double mutant highly susceptible to methylation-induced ...
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Accepted name: DNA-3-methyladenine glycosylase II. Reaction: Hydrolysis of alkylated DNA, releasing 3-methyladenine, 3-methylguanine, 7-methylguanine and 7-methyladenine. Other name(s): deoxyribonucleate 3-methyladenine glycosidase II; 3-methyladenine DNA glycosylase II; DNA-3-methyladenine glycosidase II; AlkA. Systematic name: alkylated-DNA glycohydrolase (releasing methyladenine and methylguanine). Comments: Involved in the removal of alkylated bases from DNA in Escherichia coli (cf. EC 2.1.1.63 methylated-DNA [protein]-cysteine S-methyltransferase).. Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 89287-38-7. References:. 1. Evensen, G. and Seeberg, E. Adaptation to alkylation resistance involves the induction of a DNA glycosylase. Nature 296 (1982) 773-775. [PMID: 7040984]. 2. Karran, P., Hjelmgren, T. and Lindahl, T. Induction of a DNA glycosylase for N-methylated purines is part of the adaptive response to alkylating agents. Nature 296 (1982) 770-773. ...
TY - JOUR. T1 - Inhibitory Effect of Complex Formation with Oligodeoxyribonucleotide ethyl Phosphotriesters on Transfer Ribonucleic Acid Aminoacylation. AU - Barrett, J. C.. AU - Miller, Paul S.. AU - Tso, Paul O.P.. PY - 1974/11/1. Y1 - 1974/11/1. N2 - The oligodeoxyribonucleotide ethyl phosphotriesters d-Tp(Et)Gp(Et)G and d-Tp(Et)Tp(Et)Cp(Et)A, which are complementary to the 3′-CpCpA terminus and -UpGpApA- anticodon region, respectively, of tRNAphe coli have been used as in vitro probes of the structure and function of tRNA. The effect of these triesters on the aminoacyl-tRNA synthetase catalyzed aminoacylation of tRNA was examined. At 0° both triesters inhibit the formation of phenylalanyl-tRNAphe by approximately 50-60%. The inhibition decreases with increasing temperature. A Lineweaver-Burk analysis at 0° shows that the inhibition by both triesters is competitive in nature. The results suggest that the inhibition is a consequence of the formation of complexes between the triesters and ...
Palladium is probably the most useful metal in organic syntheses. It has shown great utility in various reactions such as C-C, C-N, C-O bond formation under mild conditions. The presence of abundant amount of palladium-chemistry related literature in the form of books, reviews emphasizes the growing importance of these reagents. Nowadays organopalladium chemistry is being used in various fields such as new methodology development, natural product synthesis, synthesis of polymers. Regio- and stereoselectivity is another facet of Pd catalyzed methodologies which has been extensively utilized in the last decade to obtain enantiopure compounds. The main emphasis of this work is to utilize Pd catalyzed allylic alkylation to synthesize new heterocycles including furans, isoxazolines and new cyclopentane amino-acid analogs in an enantioselective manner. The stereochemical outcome of these reactions is influenced by desymmetrization catalyzed by hydrolytic enzymes namely lipases. Chapter 1 reviews the recent
Alkyltransferase-like proteins (ATLs) share functional motifs with the cancer chemotherapy target O(6)-alkylguanine-DNA alkyltransferase (AGT) and paradoxically protect cells from the biological effects of DNA alkylation damage, despite lacking the reactive cysteine and alkyltransferase activity of AGT. Here we determine Schizosaccharomyces pombe ATL structures without and with damaged DNA containing the endogenous lesion O(6)-methylguanine or cigarette-smoke-derived O(6)-4-(3-pyridyl)-4-oxobutylguanine. These results reveal non-enzymatic DNA nucleotide flipping plus increased DNA distortion and binding pocket size compared to AGT. Our analysis of lesion-binding site conservation identifies new ATLs in sea anemone and ancestral archaea, indicating that ATL interactions are ancestral to present-day repair pathways in all domains of life. Genetic connections to mammalian XPG (also known as ERCC5) and ERCC1 in S. pombe homologues Rad13 and Swi10 and biochemical interactions with Escherichia coli ...
The report generally describes benzyl bromoacetate, examines its uses, production methods, patents. Benzyl bromoacetate market situation is overviewed;
2. The palladium on carbon catalyst was prepared by the following method, developed by Walter H. Hartung, School of Pharmacy, University of Maryland, Baltimore. Ten milliliters of a commercial palladium chloride solution containing 0.1 g. of palladium and approximately 0.05 g. of hydrogen chloride per milliliter (obtained from the J. Bishop Company, Malvern, Pennsylvania) is added to a solution of 27 g. of sodium acetate trihydrate in 100 ml. of water. Norit (9 g.) is added, and the mixture is hydrogenated until absorption ceases. The catalyst (10 g.) is filtered on a Büchner funnel, washed with water, dried by drawing air through the funnel for about 30 minutes, and stored in a desiccator over calcium chloride. The palladium catalysts, prepared as described elsewhere in this volume, are presumably also satisfactory for the reductive alkylation described above (p. 685) ...
Block the formation of inter- and intramolecular disulfide bonds in protein samples by reductive alkylation. Improve isoelectric focusing (IEF) results.
Previous studies have shown that DNA alkylation is a common event in colorectal tissue but the source of exposure to the methylating agents remains to be identified. These results confirm our previous study in a separate population of patients with colorectal disease,8 in demonstrating that colorectal DNA, obtained from individuals with malignant colorectal disease, contains detectable amounts of the pro-mutagenic and pro-carcinogenic lesionO 6-MedG. Furthermore, evidence from the current study indicates thatO 6-MedG levels vary within the large bowel as (i) DNA alkylation was higher in normal tissue from the sigmoid colon and rectum than in the proximal colon, (ii) only 13% of paired normal and tumour DNA samples obtained from the proximal colon were both alkylated compared with 21% in the sigmoid colon and 42% in the rectum, and (iii) O 6-MedG levels in tumour DNA from the proximal colon (but not the sigmoid colon or rectum) were greater than those in normal DNA.. A number of different ...
Several xenobiotics caused hepatic porphyrin accumulation through mechanism-based inactivation of cytochrome P450(P450) and heme alkylation. Loss of iron from the alkylated heme results in formation of an N-alkylporphyrin, which is a potent inhibitor of ferrochelatase. N-Vinylprotoporphyrin IX (N-vinylPP) was identified in chick embryo liver after in ovo administration of 3-[(arylthio)ethyl]sydnone (TTMS). Pretreatment of chick embryos with beta-naphthoflavone, which causes a 90-fold increase in P450 1A levels, did not increase the formation of N-vinylPP after TTMS administration, showing that the heme moiety of P450 1A does not contribute to the formation of N-vinylPP. Increased amounts of N-vinylPP were isolated from dexamethasone-, phenobarbital-, and glutethimide-pretreated chick embryos, and it is possible that P450 2H and/or a P450 3A-like isozyme contributes to the formation of N-vinylPP. The ring B-substituted (NB) regioisomer of N-vinylPP constituted the lowest percentage of the total ...
Alkylating agents constitute a large class of DNA‐damaging agents that generate both mutagenic and cytotoxic DNA lesions. Much of our understanding of alkylation damage repair is from studies on Escherichia coli, in particular on the adaptive (Ada) response, which involves the upregulation of four genes: ada, aidB, alkA and alkB (Sedgwick et al, 2007). The Ada protein is a multifunctional DNA methyltransferase that also acts as a transcriptional activator of the response. The exact function of AidB, a flavin‐binding protein, remains to be explained and AlkA is a DNA glycosylase with a broad specificity. AlkB catalyses the demethylation of 1‐methyladenine and 3‐methylcytosine in DNA and RNA, coupled to the decarboxylation of 2‐oxoglutarate (2OG) to succinate and CO2 (Falnes et al, 2002; Trewick et al, 2002). Homologues of AlkB have been identified in species ranging from bacteria to humans; eight human homologues (ABH) have been described, but only two, ABH2 and ABH3, are known to ...
Several lines of evidence point to the existence of endogenous cellular compounds that can alkylate DNA and cause spontaneous, alkylation-induced mutation. First, the alkyl lesionsO 6MeG and 7MeG have been detected in DNA from humans, mice, and rats that were not patently exposed to alkylating agents (16, 24, 33, 44). The 3MeA free base can also be found in human urine, and some of this 3MeA burden is believed to result from release of endogenously alkylated DNA bases (24,34). Second, bacteria and yeast that are deficient in the DNA methyltransferases that repair mutagenic O 6MeG lesions display elevated spontaneous mutation rates (20, 36, 45,47, 51-53). In E. coli, the majority of the ada ogt-dependent spontaneous mutations have been shown to be G:C-to-A:T transitions (20, 47), consistent with their arising from replication past endogenous O 6MeG residues (20).. In 1996, Taverna and Sedgwick (45) reported that ada ogt E. coli defective in the moa gene, which encodes a cofactor involved in ...
In a view to develop new DNA alkylating antitumour drugs, evaluating the precise mechanism of action and the molecular/cellular consequences of the alkylation is a point of major interest. The benzo-b-acronycine derivative S23906-1 alkylates guanine nucleobases in the minor groove of the DNA helix and presents an original ability to locally open the double helix of DNA, which appears to be associated with its cytotoxic activity. However, the molecular mechanism linking adduct formation to cellular consequences is not precisely known. The objective of the present study was to identify proteins involved in the recognition and mechanism of action of S23906-DNA adducts. We found that GAPDH (glyceraldehyde-3-phosphate dehydrogenase) is a protein that binds to S23906-alkylated single-stranded, double-stranded and telomeric sequences in a drug-dependent and DNA sequence/structure-dependent manner. We used the CASTing (cyclic amplification of sequence targeting) method to identify GAPDH DNA-binding ...
The possibility that isomerization controls the fusion activity was tested by analysing Mo‐MLV fusion and infectivity under conditions that either inhibited or induced isomerization. The fusion was studied as virus‐induced polykaryon formation in XC cells (fusion‐from‐without). Fusion of cell‐bound virus is induced by incubation at 37°C and terminated by pH 3.0 treatment. In confluent cultures (Figure 6A), the fusion will merge cells, and with time these will rearrange into polykaryons (Figure 6B). Preliminary testing demonstrated that TN/1.8 mM Ca2+ supported fusion as effectively as DMEM (data not shown). Therefore, TN/1.8 mM Ca2+ was used as the control condition. The time course of the fusion process is shown in Figure 6C.. We first studied the effect that alkylation‐mediated inhibition of isomerization had on fusion. To avoid adverse effects due to alkylation of internal viral proteins, we used the membrane‐impermeant reagents M135 and MTSET. We observed a ...
1P7M: Solution structure and base perturbation studies reveal a novel mode of alkylated base recognition by 3-methyladenine DNA glycosylase I