The combination of stable isotope labelling with direct infusion ion mobility mass spectrometry (IM-MS) enabled qualitative and quantitative monitoring of biocatalytic reactions with reduced analysis times, enhanced sensitivity and μL-level assay volumes. The new approach was demonstrated by applying to both lipase and monooxygenase enzymes, including multi-substrate screening ...
We provide evidence that dietary consumption of CLA significantly improves impaired glucose tolerance in ZDF rats and that the antidiabetic effects are mediated by specific CLA isoforms. This is the first study to examine the role of specific dietary CLA isomers on food intake, growth rate, adiposity, insulin action in skeletal muscle, and expression of genes thought to be important in glucose and lipid metabolism and, perhaps, thermogenesis. Consistent with improved glucose tolerance, we show insulin-stimulated glucose transport was improved in soleus muscle, and insulin-stimulated glycogen synthase activity was improved in soleus and EDL muscles of 50:50 rats. The fact that these effects were not observed in rats fed the c9,t11 diet suggests that the effects are specific to the 10,12 CLA isomer. Additionally, the pleotrophic effects of CLA isomers on glucose and lipid metabolism in the ZDF rat model are consistent with activation of PPARs.. Several groups have previously shown that consumption ...
As the second part of our recent reinvestigation on the electronic spectra of benzene $clusters,^{a}$ we present the trimer vibronic system studied by two-color (2C) resonance enhanced two-photon ionization (R2PI) and UV-UV holeburing experiments. This band system is observed only in the dimer-ion channel even with 2C-R2PI because of extensive fragmentation after photoionization, and thus it has been incorrectly assigned to an isomeric form of the $dimer.^{b}$ Detailed examination with mixed samples of $C_{6}H_{6}$ and $C_{6}D_{6}$ has revealed that the parent neutral has a single isomeric form for each isotopomer, $(C_{6}H_{6})_{m}(C_{6}D_{6})_{n}$ with $m + n = 3$. This observation confirms the equivalency in three benzene sites, which is consistent with the most stable cyclic form predicted by a NEMO $calculation.^{c}$ One of the intermolecular modes shows prominent Franck-Condon activity, implying a substantial conformational change via photoexcitation. Other details observed in the vibrionc ...
Download summary (PDF). 1. Rodica-Mariana ION. Photodynamic therapy (PDT): a photochemical concept with medical applications. Download Art 1 (PDF). Key words: porphyrins, photodynamic therapy, singlet oxygen, porphyrins photodegradation, clinical applications. 2. Gheorghe ROMAN, Costel AGACHE, Ileana MANCIULEA, Eugenia COMANIŢĂ and Lucia DUMITRESCU. Synthesis of new Mannich bases derived from 5-phenyl-1,3,4-oxadiazole-2-thione and investigation of the conformational isomers of dimethyl 5-(5-phenyl-2-thioxo-1,3,4-oxadiazole-3-methylamino)isophthalate. Download Art 2 (PDF). Key words: oxadiazolethione, aminomethylation, Mannish base, computational chemistry, conformational isomers. 3. Simona MUNTEAN, Ludovic KURUNCZI, Valentin CAREJA and Zeno SIMON. Dissociation energies in water solution for saline bonds implied in interactions mediated by peptidoglicans. AB initio - PCM computations. Download Art 3 (PDF). Key words: peptidoglycans, intercellular interaction, saline bond, hydration energy, ...
Download summary (PDF). 1. Rodica-Mariana ION. Photodynamic therapy (PDT): a photochemical concept with medical applications. Download Art 1 (PDF). Key words: porphyrins, photodynamic therapy, singlet oxygen, porphyrins photodegradation, clinical applications. 2. Gheorghe ROMAN, Costel AGACHE, Ileana MANCIULEA, Eugenia COMANIŢĂ and Lucia DUMITRESCU. Synthesis of new Mannich bases derived from 5-phenyl-1,3,4-oxadiazole-2-thione and investigation of the conformational isomers of dimethyl 5-(5-phenyl-2-thioxo-1,3,4-oxadiazole-3-methylamino)isophthalate. Download Art 2 (PDF). Key words: oxadiazolethione, aminomethylation, Mannish base, computational chemistry, conformational isomers. 3. Simona MUNTEAN, Ludovic KURUNCZI, Valentin CAREJA and Zeno SIMON. Dissociation energies in water solution for saline bonds implied in interactions mediated by peptidoglicans. AB initio - PCM computations. Download Art 3 (PDF). Key words: peptidoglycans, intercellular interaction, saline bond, hydration energy, ...
Intro to Newman Projections - This video explains conformational isomers and how to visualize and draw Newman Projections. Also discussed are staggered and eclipsed conformations, along with a potential energy diagram for the conformational isomers of ethane from 0 - 360 degrees. Part of a full detailed Tutorial Video Series!
Isomerism - Isomerism - Cis and trans forms: The examples presented so far have concentrated on the simplest organic molecules, the alkanes. However, stereoisomers crop up in many of the other structural types of organic chemistry. For example, in the alkenes, two versions of 2-butene exist. They are traditionally called cis-2-butene and trans-2-butene or, in slightly more modern terms, (Z)- and (E)-2-butene. The Z and E stand for the German words for
Waters SYNAPT and Vion systems combine ion mobility separations with high resolution MS, significantly enhancing routine MS/MS workflows, enabling new discoveries not possible any other way
In this application note, we describe the characterization of the distribution and content of mono-di- and tetra-glycosides in the raw material or processed products to illustrate how the quality and potency of ginseng products can be determined.
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We report on gas-phase experiments investigating the predissociation and possible IR-driven isomerization of the 3-aminophenol-ammonia complex (3-AP-NH$_{3}$). A molecular beam of 3-AP-NH$_{3}$ is vibrationally excited with pulsed IR light, initiating an intramolecular vibrational redistribution and subsequent dissociation. The 3-AP fragment is then probed state-selectively via multiphoton ionization (REMPI) and time-of-flight mass spectrometry. Of particular interest is an IR-driven feature which we associate tentatively with a trans-cis isomerization process. We see clear correlation between the excitation of specific vibrational modes (namely the NH$_{3}$ symmetric and OH stretches) and the presence of this feature, as evidenced by IR-action and IR-depletion spectra. The feature persists atop a broader signal which we assign to the predissociation of the complex and whose cutoff in REMPI-action experiments provides an upper bound on the dissociation energy for 3-AP-NH$_{3 ...
5 and 6 have the same molecular formula and the same structural formula and, therefore, stereoisomers. 5 and 6 are not mirror images of each other. Thus, they are daiastereomers.. Cis-Trans isomers are a subset of diastereomers; all cis-trans isomers are diastereomers, but not all diastereomers are cis-trans isomers.. see also enantiomers. ...
TY - JOUR. T1 - Supramolecular solids as a medium for single-crystal-to-single-crystal E/Z photoisomerization. T2 - Kinetic study of the photoreactions of two Zn-coordinated tiglic acid molecules. AU - Zheng, Shao Liang. AU - Velde, Christophe M.L.Vande. AU - Messerschmidt, Marc. AU - Volkov, Anatoliy. AU - Gembicky, Milan. AU - Coppens, Philip. PY - 2008. Y1 - 2008. N2 - [Zn(TA)2(H2O)2] (H-TA = tiglic acid) has been embedded in a framework composed of CECR (CECR = C-ethylcalix[4] resorcinarene) molecules to examine its E→Z photoisomerization in a periodic framework. The photoisomerization of tiglic acid in CECR-[Zn(TA) 2(H2O)2]·4H2O proceeds without the [2 + 2]-dimerization reaction that often occurs in crystals of uncomplexed analogues, and without breakdown of the crystal lattice thatfrequently occurs in neat crystals. The two Zn-coordinated TA molecules are located in different size cavities. The rate constants of the isomerization reaction are strongly affected by the size of the ...
In chemistry, conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about formally single bonds (refer to figure on single bond rotation). While any two arrangements of atoms in a molecule that differ by rotation about single bonds can be referred to as different conformations, conformations that correspond to local minima on the energy surface are specifically called conformational isomers or conformers.[1] Rotations about single bonds involve overcoming a rotational energy barrier to interconvert one conformer to another. If the energy barrier is low, there is free rotation[2] and a sample of the compound exists as a mixture of multiple conformers; if the energy barrier is high enough then there is restricted rotation, a molecule may exist for a relatively long time period as a stable rotational isomer or rotamer. When the time scale for interconversion is long enough for isolation of individual rotamers (usually arbitrarily defined ...
1KV0: Structural mechanism governing cis and trans isomeric states and an intramolecular switch for cis/trans isomerization of a non-proline peptide bond observed in crystal structures of scorpion toxins.
Question: Two structural isomers are formed when 2-methyl-1,3-butadiene reacts with ethyl acrylate (ethyl 2-propenoate). Draw structures for these.
Ellipticine and its derivatives are molecules which possess potent anticancer activity. This thesis explores the synthesis of novel ellipticine derivatives, as well as modifications of the template, and evaluates their biological activity as anticancer agents. The first section of this work, expands on previous work within the group, exploring derivatisation at the 9-position of the ellipticine template. This methodology was then extended to encompass isoellipticine and neoellipticine, two of the isomeric forms of ellipticine. This range of analogues allows for assessment of the role of the pyridine nitrogen for bioactivity and explores the theme of D-ring modification. A panel of novel ellipticinium salts were generated, which encompass a range of substituents at the N-2, N-6 and C-9 position. To further explore the role of the D-ring, three anhydrides were subjected to the methodology for the synthesis of ellipticine but none of the coupling reactions proved successful. However, by ...
The present invention of compounds of formula (I) ##STR00001## a stereochemically isomeric form thereof, an N-oxide form thereof or a pharmaceutically acceptable acid addition salt thereof. Processes for preparing said products, formulations comprising said products and their use as a medicine are disclosed, in particular for treating conditions which are related to impairment of gastric emptying.
Pang XQ, Jia CX, Chen ZW, Li LJ. Structural Characterization of Monomers and Oligomers of D-Amino Acid-Containing Peptides Using T-Wave Ion Mobility Mass Spectrometry. Journal of the American Society for Mass Spectrometry. 2017 ;28:110-118. ...
Collision cross sections obtained with ion mobility mass spectrometry as new descriptor to predict blood-brain barrier permeation by drugs ...
In the Lindemann chemical kinetic treatment of the isomerization of molecule A to its isomer B, as in the isomerization reaction of cyclopropane to propene
Energetic and Constitutional Hysteresis in Bistable Molecules By Ulrich K d k * Bistable or multistable systems, so-called flip-flops, which remain in a state Z, until they are converted by a trigger signal into a second state Z,, are the key building blocks of all digital electronic devices. Taube and S a n ~ [have ~ recently realized such a system at the molecular level in an elegant way in the form of a dinuclear Ru-sulfide/Ru-sulfoxide complex. In principle, any isomeric pair whose isomers are separated by a sufficiently high activation energy barrier constitutes such a bistable chemical system. However, the interconversion of the isomers can involve complicated chemical operations, including even chemical degradation and synthesis with the breaking and making of bonds; such conversions can no longer be considered as being equivalent to electrical triggering. Molecules which photochemically isomerize and undergo thermal reconversion approach more closely the ideal of a triggerable ...
The column was 30 cm long, 2 in. I.D., packed with 10 mm particles carrying Vancomycin as the chiral stationary phase. The mobile phase was ethanol and the flow rate 100 ml/minute. The sample load was 400 mg dissolved in 5 ml of ethanol.. It is seen in figure 21 that after the first cycle, there is very little resolution of the enantiomers, but an impurity is separated on the front of the composite peak. This peak is diverted to waste a procedure that is termed peak shaving (from the main peak). During the second cycle, the separation of the enantiomers is beginning, although the isomers are insufficiently resolved for peak collection to be initiated. During the third cycle, the first major peak is shaved from the composite peak. It is important to note that as the overloaded peak is asymmetrical and tails, the first peak will be collected virtually pure. The second peak will remain contaminated with a small amount of the first peak. After the fourth cycle is complete, the trace of the first ...
These compounds are optically active and can rotate the plane polarized light. Thus it is also known as optical isomerism. The isomer which can rotate the plane polarized light from left to right (or clockwise) is known as dextrorotatory and which can rotate from right to left (or anticlockwise) is known as laevorotatory. A equal mixture of two enantiomer is known as racemic mixture. Such a mixture is optically inactive as they rotate the plane polarized light in opposite direction and thus cancel each other.. ...
In organic chemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon. The suffix -yl (meaning attached to) is used when naming organic compounds that contain a substituent. Additionally, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent is attached to when such information is needed to distinguish between structural isomers. The polar effect exerted by a substituent is a combination of the inductive effect and the mesomeric effect. Additional Steric effects result from the volume occupied by a substituent. The phrases most-substituted and least-substituted are frequently used to describe molecules and predict their products. For example: ...
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4-EMC ( 4-Ethylmethcathinone ) is a recreational designer drug of the stimulant and entactogen class. It is a structural isomer of 4-MEC.
(2011) Ugajin et al. American Journal of Pathology. Prostaglandin (PG) D2 and PGE2 are arachidonic acid metabolites that are generated though an isomerization reaction catalyzed by PG synthases. PGs have been implicated in immunologic reactions in addition to a wide range of physiological functio...
Dive into the research topics of An Ab initio study of the excited states, isomerization energy profiles and conical intersections of a chiral cyclohexylidene derivative. Together they form a unique fingerprint. ...
d) Unless specifically excepted under this subtitle or listed in another schedule, any material, compound, mixture, or preparation that contains any quantity of the following hallucinogenic substances, or that contains any of its salts, isomers, including optical, position, and geometric isomers, or salts of isomers, whenever the existence of such salts, isomers, or salts of isomers is possible within the specific chemical designation, is a substance listed in Schedule I ...
Color plate illustrates examples of isomerism. Includes the metamerism of various oils and olefiant gas as well as the polymerism of aldehyde, acetic ether, oil of peppermint and oil of lavender.. This plate comes from…. ...
Organika Trans-Resveratrol - Organikas resveratrol contains only the active trans form of resveratrol derived from Japanese knot
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Engineering of inorganic-organic lead halide perovskites for photovoltaic applications has experienced significant advances in recent years. However, the use of the relatively expensive spiro-OMeTAD as a hole-transporting material (HTM) poses a challenge due to dopant-induced degradation. Herein we introduce
(a) Selected region ofa 350 ms NOESY spectrum of [Y]6-AII (90% H2O/10%D2O). The red and green linesdenote the NOE connectivities for the trans and cis isomers,
isomer: Chemistry Any of two or more substances that are composed of the same elements in the same proportions but differ in properties because of differences in the arrangement of atoms.
1,3-diacetylchloramphenicol: RN given refers to (R-(R*,R*))-isomer; RN for cpd without isomeric designation not avail 10/92; structure given in first source
BMIM PF6 (1-butyl-3-methylimidazolium hexafluorophosphate) and BMIM Tf2N (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) are two conventional room-temperature ionic liquids widely employed and investigated as reaction media. Despite the presence of the same imidazolium ring in their structure they are different in many chemical and physical properties due to the nature of the anions. The thermal cis-trans isomerization of an electronically activated azobenzene have been used as reaction model to compare the behavior of PF6− and Tf2N−. Rotation is the mechanism by which the investigated azobenzene is converted into the trans isomer spontaneously in the dark both in BMIM PF6 and in BMIM Tf2N. The kinetic rate constants of the process have been determined at different temperatures and the activation energies of the reaction have been calculated according to the Arrhenius and Eyring equations. The results presented herein highlight different solute-solvent interactions involving the PF6
Asbury, G. R., Klasmeier, J., and Hill Jr, H. H.: Analysis of explosives using electrospray ionization/ion mobility spectrometry (ESI/IMS), Talanta, 50, 1291-1298, 2000. Atlas, E.: Evidence for = C3 alkyl nitrates in rural and remote atmospheres, Nature, 331, 426-428, 1988. Beaver, M. R., Clair, J. M. St., Paulot, F., Spencer, K. M., Crounse, J. D., LaFranchi, B. W., Min, K. E., Pusede, S. E., Wooldridge, P. J., Schade, G. W., Park, C., Cohen, R. C., and Wennberg, P. O.: Importance of biogenic precursors to the budget of organic nitrates: observations of multifunctional organic nitrates by CIMS and TD-LIF during BEARPEX 2009, Atmos. Chem. Phys., 12, 5773-5785, https://doi.org/10.5194/acp-12-5773-2012, 2012. Brown, S. S., deGouw, J. A., Warneke, C., Ryerson, T. B., Dubé, W. P., Atlas, E., Weber, R. J., Peltier, R. E., Neuman, J. A., Roberts, J. M., Swanson, A., Flocke, F., McKeen, S. A., Brioude, J., Sommariva, R., Trainer, M., Fehsenfeld, F. C., and Ravishankara, A. R.: Nocturnal isoprene ...
These differences can be very small, as in the case of the boiling point of straight-chain alkenes, such as pent-2-ene, which is 37 °C in the cis isomer and 36 °C in the trans isomer.[4] The differences between cis and trans isomers can be larger if polar bonds are present, as in the 1,2-dichloroethenes. The cis isomer in this case has a boiling point of 60.3 °C, while the trans isomer has a boiling point of 47.5 °C.[5] In the cis isomer the two polar C-Cl bond dipole moments combine to give an overall molecular dipole, so that there are intermolecular dipole-dipole forces (or Keesom forces), which add to the London dispersion forces and raise the boiling point. In the trans isomer on the other hand, this does not occur because the two C−Cl bond moments cancel and the molecule has a net zero dipole (it does however have a non-zero quadrupole).. The two isomers of butenedioic acid have such large differences in properties and reactivities that they were actually given completely different ...
Looking for online definition of Cis-trans isomerism in the Medical Dictionary? Cis-trans isomerism explanation free. What is Cis-trans isomerism? Meaning of Cis-trans isomerism medical term. What does Cis-trans isomerism mean?
It has been shown by infra-red spectroscopic measurements that, at temperatures near the ceiling temperature, the copolymerization of sulphur dioxide with either cis- or trans-2- butene is accompanied by the geometrical isomerization of the 2-butene. The results of some kinetic studies of this latter reaction, using a vapour-pressure technique, are reported. Over the range investigated (25 to 60°C inclusive) the rate of this isomerization reaction increases with temperature according to the normal Arrhenius law, the overall energies of activation using benzoyl peroxide as the initiator being 16·5 ± 0·6 kcal mole-1 for the cis to trans isomerization and 18∙3 ± 0∙4 kcal mole-1 for the trans to cis isomerization. Prolonged reaction leads to the attainment of cis-trans equilibrium, and the value of the relevant thermodynamic functions are cis-2-butene→trans-2-butene; in liquid sulphur dioxide, xB = 0∙09; ∆H = - 1∙43 ± 0∙25 kcal mole-1, ∆S = - 2∙8 ± 0∙8 cal deg-1 mole-1. ...
The weak n→π* interaction has been proposed to explain some conformational structure. Singh, Mishra, Sharma, and Das have now provided the first spectroscopic evidence of this interactions.1 They examined the structure of phenylformate 1. This compound can exist as two conformational isomers, having the carbonyl oxygen pointing towards (cis) or away (trans) from the phenyl ring. They optimized the structures of these two conformers at M05-2X/aug-cc-pVDZ and find that the cis isomer is lower in energy by 1.32 kcal mol-1. Unfortunately, the authors do not provide the structures of these isomers, but since they are so small, I reoptimized them at ωB97XD/6-311g(d) and they are displayed in Figure 1. At this computational level, the cis isomer is lower in enthalpy than the trans isomer by 1.35 kcal mol-1.. ...
This novel and improved deconvolution method allows high-throughput, quantitative analysis of isobars from unresolved chromatographic peaks, and accurate quantification of isomers or isobars in a complex mixture. Tandem mass spectrometry is attractive for many applications due to its high selectivity, wide dynamic range, and high throughput capabilities. Analysis of isobars and isomers by tandem mass spectrometry is complicated by the similarity between their mass spectra and often requires extensive chromatographic separation in order to eliminate mutual interference, and many methods for the separation of structural isomers are not compatible for quantitative analysis.
© 2014 The Authors. Gene transcription responds to stress and metabolic signals to optimize growth and survival. Histone H3 (H3) lysine 4 trimethylation (K4me3) facilitates state changes, but how levels are coordinated with the environment is unclear. Here, we show that isomerization of H3 at the alanine 15-proline 16 (A15-P16) peptide bond is influenced by lysine 14 (K14) and controls gene-specific K4me3 by balancing the actions of Jhd2, the K4me3 demethylase, and Spp1, a subunit of the Set1 K4 methyltransferase complex. Acetylation at K14 favors the A15-P16. trans conformation and reduces K4me3. Environmental stress-induced genes are most sensitive to the changes atK14 influencing H3 tail conformation and K4me3. By contrast, ribosomal protein genes maintain K4me3, required for their repression during stress, independently of Spp1, K14, and P16. Thus, the plasticity in control of K4me3, via signaling to K14 and isomerization at P16, informs distinct gene regulatory mechanisms and processes involving
TY - JOUR. T1 - Supramolecular chemistry of cyclodextrin-peptide hybrids. T2 - Azobenzene-tagged peptides. AU - Ueno, Akihiko. AU - Shimizu, Tomoko. AU - Mihara, Hisakazu. AU - Hamasaki, Keita. AU - Pitchumani, K.. PY - 2002. Y1 - 2002. N2 - AC17, which is composed of 17 amino acids and has an azobenzene moiety but has no cyclodextrin (CD) unit in the side chain, exhibits 54% helix content. However, ACα17, which has both trans-azobenzene and α-CD, shows 82% helix content. This result suggests that the helix structure is stabilized by host (CD)-guest (azobenzene) bridge in the side chain of the peptide. The helix content changed by trans-cis photoisomerization as shown by 64% helix content for ACα17 in its cis form. This result suggests that cis-azobenzene unit is excluded from the α-CD cavity, thus resulting in the smaller helix content. The helix contents for ACβ17, which has both azobenzene and β-CD, are 94% in the cis form and 87% in the trans form, suggesting that the cis form is ...
We report the two-photon induced photoisomerization of 3-[1-(1,2- dimethyl-1H-indol-3-yl)-ethylidene]-4-isopropylidene-dihydro-furan- 2,5-dione (1), a photochromic compound with (lambda) maxequals385nm, using 775 fs pulses. The resulting photoisomer has a (lambda) maxequals582 nm. The kinectic rate contant for the isomerization reaction w as measured at two different intensities (two different powers), showing a quadratic dependence with respect to the pump intensity. Results of pump-probe solution phase experiments and guest/host polymer thin film interferometric imaging studies are shown. A two-photon absorption molecular cross-section (sigma) 2equals10.3 x 10- 45 cm4 s/photon was measured using Z-scan, supporting a two photon induced isomerization process ...
The isomerization of limonene over the Ti-SBA-15 catalyst, which was prepared by the hydrothermal method, was studied. The main products of limonene isomerization were terpinolene, α-terpinene, γ-terpinene, and p-cymene-products with numerous applications. The amount of these products depended on reaction time, temperature, and catalyst content. These parameters changed in the following range: reaction time 30-1380 min, temperature 140-160 °C, and catalyst content 5-15 wt %. Finally, the most favorable conditions for the limonene isomerization process were established: a reaction time of 180 min, temperature of 160 °C, and amount of the catalyst 15 wt %. In order to obtain p-cymene (dehydroaromatization product), the most favorable conditions are similar but the reaction time should be 1380 min. The application of such conditions allowed us to obtain the highest amounts of the desired products in the shortest time.
Looking for online definition of Conformational isomerism in the Medical Dictionary? Conformational isomerism explanation free. What is Conformational isomerism? Meaning of Conformational isomerism medical term. What does Conformational isomerism mean?
Lactate, the anion that results from dissociation of lactic acid, is an intracellular metabolite of glucose; specifically it is the end product of anaerobic glycolysis, the final step of which is conversion of pyruvate to lactate by the enzyme lactate dehydrogenase. The two lactate isomers are known as L-lactate and D-lactate. Both forms (stereoisomers) of lactate are produced from and metabolized to pyruvate by the action of the enzyme lactate dehydrogenase (LDH). However, the enzyme is isomer-specific so that production and metabolism of D-lactate requires D-LDH and L-lactate requires L-LDH. Mammalian cells only contain L-LDH so that in humans the lactate produced is almost exclusively L-lactate. Carbohydrate-fermenting bacterial species (e.g. Lactobacillus spp) have by contrast both enzymes and therefore the capacity to produce both D-lactate and L-lactate. Some species produce only D-lactate, some only L-lactate and others both forms.. L-lactate is thus normally present in human body. If ...
Proline is a non-polar proteinogenic amino acid that forms a tertiary amide when incorporated into peptides. It does not have a hydrogen on the amide group and therefore cannot act as a hydrogen bond donor. Proline is known as a classical breaker of both the α-helical and β-sheet structures in proteins and peptides. Nevertheless, it is widely distributed in the putative transmembrane domains of many protein transporters and channels, regions believed to be α-helical.1. Among the proteinogenic amino acids, proline plays a special role. In protein structures the planar peptide bond occurs predominantly in the trans conformation.2 The proline residue restricts the conformational space of the peptide chain. However, due to the small free enthalpy difference between the cis and trans Xaa-Pro bond isomers of 2.0 kJ·mol-1 (compared to 10.0 kJ·mol-1 for other Xaa-non-Pro peptide bonds), there is a relatively high intrinsic probability of 30% cis conformation at RT and both cis and trans isomers are ...
Nonene is an alkene with the molecular formula C9H18. Many structural isomers are possible, depending on the location of the C=C double bond and the branching of the other parts of the molecule. Industrially, the most important nonenes are trimers of propene ...
Herrmann J, Rubin D, Häsler R, Helwig U, Pfeuffer M, Auinger A, Laue C, Winkler P, Schreiber S, Bell D, Schrezenmeir J (2009); Lipids Health Dis., 8:35. doi: 10.1186/1476-511X-8-35. ...
Several studies suggest that conjugated linoleic acid (CLA) isomers occuring naturally in milk and meat of ruminants influence atherosclerotic processes. The aim of this study was to investigate the effects of cis-9, trans-11 CLA und trans-10, cis-12 CLA on atherosclerosis-relevant parameters, vasoactive substances and pro-inflammatory parameters, in human arterial endothelial cells. To investigate the effect of both CLA isomers on the release of vasoactive substances playing an important role for maintenance of vascular homeostasis, human aortic endothelial cells (HAoEC) were incubated with 5 or 50 µmol/L of cis-9, trans-11 CLA or trans-10, cis-12 CLA for 24 h at 37 °C. After incubation period, the fatty acid composition in total lipids and phospholipids, formation of conjugated metabolites of CLA in total lipids, parameters of the eicosanoid synthesis and the nitric oxide synthesis as well as the release of endothelin-1 were determined. Incubation of HAoEC with the CLA isomers resulted in a ...
Abstract. An olefin metathesis/double bond migration sequence of allyl ethers to cyclic enol ethers is catalyzed by first and second generation Grubbs catalysts. These ruthenium carbene complexes were activated to catalyze the double bond migration by additioin of hydride sources, such as NaH or NaBH4.. ...
Monosaccharides are the simplest form of carbohydrates. They consist of one sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose, galactose, and ribose. Monosaccharides are the building blocks of disaccharides like sucrose (common sugar) and polysaccharides (such as cellulose and starch). Further, each carbon atom that supports a hydroxyl group (except for the first and last) is chiral, giving rise to a number of isomeric forms all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but they have different chemical and physical properties. ...
Butane gas definition: a colourless flammable gaseous alkane that exists in two isomeric forms, both of which... | Meaning, pronunciation, translations and examples
The C-C bond in alkanes is a sigma bond and has cylindrical symmetry. Due to this, atoms involved can rotate about the axis of the bond without affecting the overlap of orbitals that form the bond. So rotation about C-C bond is quite free. Therefore hydrogen atoms can have different spatial arrangement while maintaing the bond and the bond angle between H-C-H. Such different spatial arrangments are called conformations, conformational isomers (conformers) or rotational isomers (rotamers ...
Our interest in the title compound, C36H27N3O9, arises from its use as an important precursor in the synthesis of artificial receptors based on trimethoxybenzene-derived core (for a review on acyclic carbohydrate receptors containing a trimethyl- or triethylbenzene scaffold, see: Mazik, 2009). The title compound crystallizes in the space group P-1 with one molecule in the asymmetric part of the unit cell. The interplanar angles between the phthalimido residues are 6.67 (4) (B/C), 48.86 (3) (B/D) and 53.23 (3)° (C/D). According to the three-dimensional arrangement of substituents around the benzene ring the present conformational isomer can be named 1-up, 3,5-down tris(phthalimidomethyl), 2,4-up, 6-down- trimethoxybenzene. The molecular conformation is stabilized by seven C-H···O hydrogen bonds (Desiraju, 2002; Desiraju & Steiner, 1999; Mazik et al., 2001; Steiner, 2002) with phthalimido O atoms O(4), O(7), O(8), O(9) and the ether O atoms O(2), O(3) acting as acceptors [C-H···Ophthal 2.38 ...
To investigate early intermediates of β2-microglobulin (β2m) amyloidogenesis, we solved the structure of β2m containing the amyloidogenic Pro32Gly mutation by X-ray crystallography. One nanobody (Nb24) that efficiently blocks fibril elongation was used as a chaperone to co-crystallize the Pro32Gly β2m monomer under physiological conditions. The complex of P32G β2m with Nb24 reveals a trans peptide bond at position 32 of this amyloidogenic variant, whereas Pro32 adopts the cis conformation in the wild-type monomer, indicating that the cis to trans isomerization at Pro32 plays a critical role in the early onset of β2m amyloid formation.. ...
For a complex compound with coordination number 4, say having square planar geometry, and say all the ligands attached to the central metal atom are different, then we know that we will get 3 geometrical isomers. Now my doubt is like in organic chemistry if we had 4 different groups around a carbon atom, we still named those isomers as Z and E isomers (by Cahn Ingold Prelog principle) . Similarly why cant we name the isomers as Z and E for the case of complex compound with square planar arrangement having four different ligands attached to it? That is why cant we name those 3 geometrical isomers as Z and E isomers of the complex compound by Cahn Ingold Prelog principle?. ...
1) PRECURSOR CHEMICALS.-The term listed precursor chemical means a chemical that may be used in manufacturing a controlled substance in violation of this chapter and is critical to the creation of the controlled substance, and such term includes any salt, optical isomer, or salt of an optical isomer, whenever the existence of such salt, optical isomer, or salt of optical isomer is possible within the specific chemical designation. The following are listed precursor chemicals:. ...
We recently reported the synthesis of NOSH-aspirin, a novel hybrid that releases both nitric oxide (NO) and hydrogen sulfide (H2S). In NOSH-aspirin, the two moieties that release NO and H2S are covalently linked at the 1, 2 positions of acetyl salicylic acid, i.e. ortho-NOSH-aspirin (o-NOSH-aspirin). In the present study, we compared the effects of the positional isomers of NOSH-ASA (o-NOSH-aspirin, m-NOSH-aspirin and p-NOSH-aspirin) to that of aspirin on growth of HT-29 and HCT 15 colon cancer cells, belonging to the same histological subtype, but with different expression of cyclooxygenase (COX) enzymes; HT-29 express both COX-1 and COX-2, whereas HCT 15 is COX-null. We also analyzed the effect of these compounds on proliferation and apoptosis in HT-29 cells. Since the parent compound aspirin, inhibits both COX-1 and COX-2, we also evaluated the effects of these compounds on COX-1 and COX-2 enzyme activities and also performed modeling of the interactions between the positional isomers of NOSH-aspirin
Hexane can form five isomers with its six carbon bonds. The five isomers are 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane and hexane itself, which is a straight chain of...
Generation of irregular time series based on physical processes is indispensable in computing and artificial intelligence. In this report, we propose and demonstrate the generation of Schubert polynomials, which are the foundation of versatile permutations in mathematics, via optical near-field processes introduced in a photochromic crystal of diarylethene combined with a simple photon detection protocol. Optical near-field excitation on the surface of a photochromic single crystal yields a chain of local photoisomerization, forming a complex pattern on the opposite side of the crystal. The incoming photon travels through the nanostructured photochromic crystal, and the exit position of the photon exhibits a versatile pattern. We emulated trains of photons based on the optical pattern experimentally observed through double-probe optical near-field microscopy, where the detection position was determined based on a simple protocol, leading to Schubert matrices corresponding to Schubert polynomials. The
Plays a crucial role in plant growth and development. Is essential for the biosynthesis of carotenoids. Carotenoids are involved in different physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid (ABA) and chloroplast biogenesis (PubMed:17468780, PubMed:24907342). Catalyzes the conversion of zeta-carotene to lycopene via the intermediary of neurosporene. It carries out two consecutive desaturations (introduction of double bonds) at positions C-7 and C-7. Shows stereoselectivity toward trans C15-C15zeta-carotene double bond. The zeta-carotene produced by the phytoene desaturase PDS has a C15-C15 double bond in the cis configuration and it requires isomerization before being recognized as substrate by ZDS. The main product is 7,9,7,9-tetra-cis-lycopene (pro-lycopene) (PubMed:9914519 ...
The bachelor thesis is about cis-trans isomerization of Xaa-Pro (Xaa = any amino acid), their quantitative acquisition and the selection of 3D structure information for the prediction with a support vector machine (SVM). The quantitative detection of occurrence of cis-, trans- and cis/trans conformation in membrane proteins will be examined and evaluated. The 3D structure informa-tions include 12 features, the amino acids around proline and are including of proline. These include the inside/outside classification, the real secondary structure, energy consideration, as well as five further amino acid occur properties within a defined radius of the proline. From this information, a data set was created for the SVM. This program is used for the prediction of unknown and known Xaa Pro Isomerisms. The methods for the analysis were implemented with the platform independent programming language Java. Two programs have emerged from the work to a Xaa PIPT for the quantitative detection and extracting ...
Google Scholar Citations to the following publications. 35) Kim S, Kim Y, Suh DH, Lee CH, Yoo SM, Lee SY, and Yoon SH Heat-responsive and time-resolved transcriptome and metabolome analyses of Escherichia coli uncover thermo-tolerant mechanisms Scientific Reports 10(1):17715 (2020.10.19). 34) Kim H, Kim S, Kim D, and Yoon SH A single amino acid substitution in aromatic hydroxylase (HpaB) of Escherichia coli alters substrate specificity of the structural isomers of hydroxyphenylacetate BMC Microbiology 20:109 (2020.05.06). 33) Sarak S, Jeon H, Patil MD, Khobragade TP, Pagar AD, Sung S, Yoo H-W, Kim B-G, Yoon SH, and Yun H Enzymatic synthesis of aliphatic primary ω-amino alcohols from ω-amino fatty acids by carboxylic acid reductase Catalysis Letters 150:3079-3085 (2020.04.25) 32) Kim E-Y, Ashlock D, and Yoon SH Identification of critical connectors in the directed reaction-centric graphs of microbial metabolic networks BMC Bioinformatics 20:328 (2019.06). 31) Kim S, Kim Y, and Yoon SH ...
CLA stands for Conjugated Linoleic Acid. When it comes to burning fat and gaining muscle, CLA is quickly becoming the most necessary supplement to help people achieve those goals. Every single softgel of Optimum Nutrition CLA contains 1000 mg of CLA One. This equates to 750 mg of total CLA and 700 mg of active isomers.
A new type of isomerism has been detected in the cyclidene family of lacunar dioxygen carriers, providing an additional Structural variable for the central of their oxygen affinity. In those rare complexes that do not have methyl substituents on the primary macrocycle, NMR and X-ray crystallographic data indicate that, in addition to their usual cis orientation, the bridges can also adopt a trans orientation. In the crystal structure of [Co(C8MeHH[16]cyclidene)](PF6)(2) . 3CH(3)OH, the bridge has this trails orientation with one end in the lid-on configuration while the other end is lid-off. The trans orientation of the bridge is identified as the principal cause of the decreased dioxygen affinity of such unsubstituted cyclidenes.. ...
This is because the carbocation formed in the rate determining step (b) (i), has a trigonal planar arrangement of C-R bonds around the C+ carbon, so the hydroxide ion (or water) can attack each side of the carbocation with equal probability, giving equal amounts of each possible optical isomer. The two optically activities cancel each other out, so zero rotation of plane polarised light ...
Abstract: Reactions of the BH4- anion with equimolar amounts of HN(NO2)2 or of BH3*THF with K+[N(NO2)2]- produced a mono-substituted [BH3N(NO2)2]- anion which contains a B-N connected dinitramido ligand. The reaction of BH4- with two equivalents of HN(NO2)2 afforded the di-substituted borate anion consisting of two isomers, one with both nitramido ligands attached to B through N and the other one with one ligand attached through N and the other one through O. The disubstituted dinitramidoborates are marginally stable under ambient conditions, and the isomer with two N-connected ligands was characterized by its crystal structure. A tri-substituted borate was tentatively identified by NMR in the reaction of BH4- with a large excess of HN(NO2)2. All anions are highly energetic. Theoretical calculations show that the energy differences between the B-N and B-O tautomers are small, explaining the observed ease of ligand exchange.
As illustrated in this figure, the three isomers share a common overall metabolic pathway, but there are also important differences that can potentially affect their pharmacological effects. All three positional isomers initially undergo a rapid deacetylation that is essentially complete within 5 min. Although this is not immediately apparent from the liver data, it is, nevertheless, very clear from our study of the rat colon where these processes are slower than in the liver. This step is the same as the deacetylation of traditional aspirin, which is also rapid (Insel, 1996). Following deacetylation, the ester bond between the two benzene rings is cleaved but at different rates among the three isomers, being slower for the ortho-isomer than for the other two; the rates for meta- and para-isomers are roughly equal.. The next step differs dramatically among the three isomers. For the meta-isomer, the deacetylated derivative of NO-ASA is hydrolyzed to salicylic acid and 3-NMP, both of which are ...
Three positional isomers of a Schiff base containing -OH as end groups have been synthesized and evaluated for selective Al(iii) detection due to inhibition of ESIPT, PET and activation of CHEF in 70% aqueous medium. Devoid of any conventional fluorophore, these sensors have nanomolar detection limits with h
Ambidentate ligands have more than one binding site. Both NO2 and SCN are ambidentate ligands and will therefore show linkage isomerism. ...
This Chemistry Factsheet will allow you to: • Recognise the differences between different types of isomerism. • Have had the opportunity to see some worked examples of typical exam questions on this topic.
Aleskerov, M.A., Yufit, S.S. & Kucherov, V.F. Isomerization of diastereomers ofβ-alkoxy ketoesters in acetic acid. Russ Chem Bull 21, 2573 (1972). https://doi.org/10.1007/BF00850133. Download ...
Aleskerov, M.A., Yufit, S.S. & Kucherov, V.F. Isomerization of diastereomers ofβ-alkoxy ketoesters in acetic acid. Russ Chem Bull 21, 2573 (1972). https://doi.org/10.1007/BF00850133. Download ...
A vitamin-like compound also called ubiquinone, coenzyme Q10 is an essential component of cells and is involved in the production of ATP. NOW Foods only uses the trans form of...
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Reaction of Ph3P+C-HR with R1CHO at -78 Deg yielded Ph3P+CHRCHR1O- (I). Subsequent addn. of BuLi gave Ph3P+C-RCHR1O- Li+ (II). Reaction of II with HCl and hydrolysis with tert-BuOK gave .apprx.80% RCH:CHR1 (R = Et, Ph, or C5H11; R1 = Me, Et, or C5H11). When the reaction was performed in the presence of LiClO4, nearly pure trans isomer was obtained, while in the absence of Li salts reaction was not stereoselective, indicating that Li salts favored the threo form of I. Na salts had a similar effect. [on SciFinder (R)] Schlosser, Manfred; Christmann, Karl F.; Piskala, Alois