Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a family of proteins present on the membrane surface of red blood cells (RBCs or erythrocytes) that are infected by the malarial parasite Plasmodium falciparum. PfEMP1 is synthesized during the parasites blood stage (erythrocytic schizogony) inside the RBC, during which the clinical symptoms of falciparum malaria are manifested. Acting as both an antigen and adhesion protein, it is thought to play a key role in the high level of virulence associated with P. falciparum. It was discovered in 1984 when it was reported that infected RBCs had unusually large-sized cell membrane proteins, and these proteins had antibody-binding (antigenic) properties. An elusive protein, its chemical structure and molecular properties were revealed only after a decade, in 1995. It is now established that there is not one but a large family of PfEMP1 proteins, genetically regulated (encoded) by a group of about 60 genes called var. Each P. falciparum is ...
BioAssay record AID 404888 submitted by ChEMBL: Inhibition of Plasmodium falciparum DHODH assessed as reduction of 2,6-dichloroindophenol by competitive binding assay.
The Plasmodium falciparum Merozoite Surface Protein 1(Pf MSP1), a predominant antigen on the surface of the asexual blood stage of the parasite, plays a role in erythrocyte invasion. It elicits immune responses during exposure to natural P. falciparum infections, hence, it is a potential vaccine candidate. However, its extensive sequence diversity causes antigenic variability. Parasites that express variants other than that targeted by immune protection mounted as a result of a vaccine variant, evade the resultant host immune protection. This compromises the efficacy of allele-specific vaccines formulated to protect against a single variant. Due to this, Pf MSP1 has been extensively studied, including in Kenya. However, the extent of Pf MSP1 diversity in children with multiple infections are unknown in Kilifi which is a moderate to high malaria transmission zone. Parasite genomic DNA was extracted from 421 blood samples in 33 children aged below 5 years who had at least 9 multiple infections. ...
Pulmonary oedema (PE) is a serious complication of Plasmodium falciparum malaria which can lead to acute lung injury in severe cases. Lung macrophages are activated during malaria infection due to a complex host-immune response. The molecular basis for macrophage polarization is still unclear but understanding the predominant subtypes could lead to new therapeutic strategies where the diseases present with lung involvement. The present study was designed to study the polarization of lung macrophages, as M1 or M2 macrophages, in the lungs of severe P. falciparum malaria patients, with and without evidence of PE. Lung tissue samples, taken from patients who died from severe P. falciparum malaria, were categorized into severe malaria with PE and without PE (non-PE). Expression of surface markers (CD68+, all macrophages; CD40+, M1 macrophage; and CD163+, M2 macrophage) on activated lung macrophages was used to quantify M1/M2 macrophage subtypes. Lung injury was demonstrated in malaria patients with PE. The
The surface-accessible ectodomain region of the Plasmodium falciparum apical membrane antigen 1 (AMA1) is a malaria vaccine candidate. The amino acid sequence may be under selection from naturally acquired immune responses, and previous analyses with a small number of allele sequences indicate a non-neutral pattern of nucleotide variation. To investigate whether there is selection to maintain polymorphism within a population, and to identify the parts of the ectodomain under strongest selection, a sample of 51 alleles from a single endemic population was studied. Analyses using Fu and Lis D and F tests, Tajimas D test, and the McDonald-Kreitman test (with the chimpanzee parasite P. reichenowi as outgroup) show significant departure from neutrality and indicate the selective maintenance of alleles within the population. There is also evidence of a very high recombination rate throughout the sequence, as estimated by the recombination parameter, C, and by the rapid decline in linkage disequilibrium with
Download Video Enzymes (Part 3 Of 5) - Lineweaver Burk Plot - Double Reciprocal Plot 1080p 720p 480p MP4 FLV 3GP MP3, Download LaguEnzymes (Part 3 Of 5) - Lineweaver Burk Plot - Double Reciprocal Plot Lengkap Terbaru
TY - JOUR. T1 - Photoinduced electron-transfer processes between phthalocyanines and perylene derivatives. AU - Kitazume, Koji. AU - Chen, Yu. AU - Itou, Mitsunari. AU - Araki, Yasuyuki. AU - Uchida, Satoshi. AU - Ito, Osamu. PY - 2006/1/1. Y1 - 2006/1/1. N2 - Photoinduced electron-transfer processes between phthalocyanines (H 2Pc and ZnPc) as electron donors and perylene derivatives as electron acceptors have been studied using a time-resolved, nanosecond transient absorption method in benzonitrile. The observed findings show that intermolecular electron transfer takes place via the excited triplet states of ZnPc and H2Pc, as confirmed by the characteristic transient absorption bands in the near-IR region. The visible light excitation of the mixtures of H2Pc and the perylene derivatives adsorbed onto TiO 2 gave a relatively high photovoltaic efficiency.. AB - Photoinduced electron-transfer processes between phthalocyanines (H 2Pc and ZnPc) as electron donors and perylene derivatives as electron ...
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The ndhB- and psaE- mutants of the cyanobacterium Synechocystis sp. PCC 6803 are partly deficient in PSI-driven cyclic electron transport. We compared photoinhibition in these mutants to the wild type to test the hypothesis that PSI cyclic electron transport protects against photoinhibition. Photoinhibitory treatment greatly accelerated PSI cyclic electron transport in the wild type and also in both the mutants. The psaE- mutant showed rates of PSI cyclic electron transport similar to the wild type under all conditions tested. The ndhB- mutant showed much lower rates of PSI cyclic electron transport than the wild type following brief dark adaptation but exceeded wild type rates after exposure to photoinhibitory light. The wild type and both mutants showed similar rates of photoinhibition damage and photoinhibition repair at PSII. Photoinhibition at PSI was much slower than at PSII and was also similar between the wild type and both mutants, despite the known instability of PSI in the psaE- ...
Induced degradation of Malathion in aqueous solutions with advanced oxidation processes (AOPs), using ultraviolet irradiation (UV), ozonation and chemical oxidation using (sodium hypochlorite, calcium hypochlorite, monochloride-isocyanuric acid (MCICA), dichloroiso-cyanuric acid (DCICA), trichloroisocyanuric acid (TCICA) was studied. Malathion and its degradation products were extracted using solid phase extraction (SPE) method, identified using GC-MS. Results showed that the degradation of malathion in aqueous solutions followed the first order reaction, and its half life was 2.37, 4.53, 6.64 and 8.84 h under ozonation, UV, 1.5% TCICA and 1.5% DCICA, respectively when malathion solutions treated for 12 h. The concentrations of chemical oxidative substances, active chlorine content and time of treatments had a significant effect on degradation rate of Malathion, which increased with increasing of each. The most enhancement of Malathion degradation was observed in treatment with ozonation, UV, ...
Natural Electron ACCEPTORS Nicotinamide Adenine Dinucleotide Phosphate (NADP) used in photosynthesis in chloroplasts NADP + + 2H + + 2e - NADPH + H + Ferredoxin the most difficult to reduce (and most easily oxidised) Cytochromes Conjugate proteins which contain a haem group. The iron atom undergoes redox reactions Fe 3+ + e - Fe 2+ NB The iron atom in the haem group of haemoglobin does not go through a redox reaction Haemoglobin is oxygenated or deoxygenated Reduction Oxidation Reduction Oxidation © 2010 Paul Billiet ODWSODWS
TY - JOUR. T1 - Reduced Cardiac Index Reserve and Hypovolemia in Severe Falciparum Malaria. AU - Kingston, Hugh W.F.. AU - Ghose, Aniruddha. AU - Rungpradubvong, Voravut. AU - Satitthummanid, Sudarat. AU - Herdman, M. Trent. AU - Plewes, Katherine. AU - Leopold, Stije J.. AU - Ishioka, Haruhiko. AU - Mohanty, Sanjib. AU - Maude, Richard J.. AU - Schultz, Marcus J.. AU - Lagrand, Wim K.. AU - Hossain, Md Amir. AU - Day, Nicholas P.J.. AU - White, Nicholas J.. AU - Anstey, Nicholas M.. AU - Dondorp, Arjen M.. PY - 2020/5/1. Y1 - 2020/5/1. N2 - Background: Impaired microvascular perfusion is central to the development of coma and lactic acidosis in severe falciparum malaria. Refractory hypotension is rare on admission but develops frequently in fatal cases. We assessed cardiac function and volume status in severe falciparum malaria and its prognostic significance. Methods: Patients with severe (N = 101) or acute uncomplicated falciparum malaria (N = 83) were recruited from 2 hospitals in India and ...
BACKGROUND: Gametocytes are responsible for transmission of malaria from human to mosquito. Artemisinin combination therapy (ACT) reduces post-treatment gametocyte carriage, dependent upon host, parasite and pharmacodynamic factors. The gametocytocidal properties of antimalarial drugs are important for malaria elimination efforts. An individual patient clinical data meta-analysis was undertaken to identify the determinants of gametocyte carriage and the comparative effects of four ACTs: artemether-lumefantrine (AL), artesunate/amodiaquine (AS-AQ), artesunate/mefloquine (AS-MQ), and dihydroartemisinin-piperaquine (DP). METHODS: Factors associated with gametocytaemia prior to, and following, ACT treatment were identified in multivariable logistic or Cox regression analysis with random effects. All relevant studies were identified through a systematic review of PubMed. Risk of bias was evaluated based on study design, methodology, and missing data. RESULTS: The systematic review identified 169 published
TY - JOUR. T1 - Rate constants and kinetic deuterium isotope effects for hydrogen atom abstraction from phenols by polyvinyl acetate radical. AU - Simonyi, Miklós. AU - Fitos, Ilona. AU - Kardos, Julianna. AU - Lukovits, István. AU - Pospišil, Jan. PY - 1975/1/1. Y1 - 1975/1/1. N2 - The primary kinetic deuterium isotope effect (PKIE) for the hydrogen atom abstraction from substituted phenols by polyvinyl acetate radical shows a large variation, and shows a maximum as a function of the reactivity of the compounds; the high values of PKIE may be attributed to tunnelling.. AB - The primary kinetic deuterium isotope effect (PKIE) for the hydrogen atom abstraction from substituted phenols by polyvinyl acetate radical shows a large variation, and shows a maximum as a function of the reactivity of the compounds; the high values of PKIE may be attributed to tunnelling.. UR - http://www.scopus.com/inward/record.url?scp=37049127504&partnerID=8YFLogxK. UR - ...
Nitrate reductase (NR), a key enzyme in nitrogen metabolism, has been implicated in the production of nitric oxide (NO) in plants. The effect of photosynthetic electron transport chain inhibitors and NO scavengers or donors on NR activity of Gracilaria chilensis was studied under experimental laboratory conditions. Effective quantum yield (I broken vertical bar (PSII)) and NR activity were significantly diminished by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, two photosynthetic electron flux inhibitors of photosystem (PS) II and PSI, respectively, but not by diphenyleneiodonium, a NADPH oxidase inhibitor, indicating a direct dependence of NR activity on the PSII and PSI electron flux. Nitrate reductase activity was sensitive to a decrease or increase of NO levels when NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and NO donor (sodium nitroprusside) were added. Moreover, the addition of 8Br-cGMP, a secondary ...
Component of a complex that catalyzes the oxidation of glycolate to glyoxylate (PubMed:4557653, PubMed:8606183). Is required for E.coli to grow on glycolate as a sole source of carbon (PubMed:8606183). Is also able to oxidize D-lactate ((R)-lactate) with a similar rate (PubMed:4557653). Does not link directly to O(2), and 2,6-dichloroindophenol (DCIP) and phenazine methosulfate (PMS) can act as artificial electron acceptors in vitro, but the physiological molecule that functions as primary electron acceptor during glycolate oxidation is unknown (PubMed:4557653).
Inhibition of polyamine biosynthesis and/or the perturbation of polyamine functionality have been exploited with success against parasitic diseases such as Trypanosoma infections. However, when the classical polyamine biosynthesis inhibitor, α-difluoromethylornithine, is used against the human malaria parasite, Plasmodium falciparum, it results in only a cytostatic growth arrest. Polyamine metabolism in this parasite has unique properties not shared by any other organism. These include the bifunctional arrangement of the catalytic decarboxylases and an apparent absence of the typical polyamine interconversion pathways implying different mechanisms for the regulation of polyamine homeostasis that includes the uptake of exogenous polyamines at least in vitro. These properties make polyamine metabolism an enticing drug target in P. falciparum provided that the physiological and functional consequences of polyamine metabolism perturbation are understood. This review highlights our current ...
TY - JOUR. T1 - Photoinduced electron transfer within a zinc porphyrin-cyclobis(paraquat-p-phenylene) donor-acceptor dyad. AU - Fathalla, Maher. AU - Barnes, Jonathan C.. AU - Young, Ryan M.. AU - Hartlieb, Karel J.. AU - Dyar, Scott M.. AU - Eaton, Samuel W.. AU - Sarjeant, Amy A.. AU - Co, Dick T.. AU - Wasielewski, Michael R.. AU - Stoddart, J. Fraser. PY - 2014/11/3. Y1 - 2014/11/3. N2 - Understanding the mechanism of efficient photoinduced electron-transfer processes is essential for developing molecular systems for artificial photosynthesis. Towards this goal, we describe the synthesis of a donor-acceptor dyad comprising a zinc porphyrin donor and a tetracationic cyclobis(paraquat-p-phenylene) (CBPQT4+ ) acceptor. The Xray crystal structure of the dyad reveals the formation of a dimeric motif through the intermolecular coordination between the triazole nitrogen and the central Zn metal of two adjacent units of the dyad. Photoinduced electron transfer within the dyad in MeCN was ...
TY - JOUR. T1 - Effects of NH4F concentrations of electrolytes and reaction time in the anodic oxidation process on the photovoltaic properties of back-illuminated DSSC. AU - Chang, Ho. AU - Kao, Mu Jung. AU - Kuo, Chin-Guo. AU - Chou, Cheng Yi. PY - 2014/1/1. Y1 - 2014/1/1. N2 - This study develops photoelectrode thin film needed in back-illuminated dye-sensitized solar cells (DSSC) by the anodization method. We test the effects of electrolytes with different NH4F concentrations reaction time lengths in the anodic oxidation process on the photoelectric conversion efficiency of DSSC, and measure the open-circuit voltage decay, lifetime of electrons and incident photontoelectron conversion efficiency (IPCE) of the prepared DSSC. Experimental results show that the TiO2 nanotube thin film prepared by anodic oxidation with an electrolyte with a NH4F concentration at 0.75 wt% and with a reaction time of 5 hr achieves a photoelectric conversion efficiency of 3.98%, open-circuit voltage of 0.723 V, and ...
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TY - JOUR. T1 - Axle length effect on photoinduced electron transfer in triad rotaxane with porphyrin, [60]fullerene, and triphenylamine. AU - Sandanayaka, Atula S.D.. AU - Sasabe, Hisahiro. AU - Araki, Yasuyuki. AU - Kihara, Nobuhiro. AU - Furusho, Yoshio. AU - Takata, Toshikazu. AU - Ito, Osamu. PY - 2010/4/29. Y1 - 2010/4/29. N2 - Photoinduced multiple electron-transfer processes of a newly synthesized rotaxane with one acceptor and two donors are studied with the time-resolved fluorescence and absorption methods. In this rotaxane, zinc porphyrin (ZnP) with a crown-ether necklace is employed as a photosensitized electron donor; through the crown-ether, a short axle with C60 and triphenylamine (TPA) at both terminals is penetrating as an electron acceptor and a hole-shift, respectively (abbreviated as (ZnP;C60-(AS)-TPA) Rot). The time-resolved fluorescence and transient absorption measurements reveal that the through-space electron-transfer processes take place via the excited states of the ...
TY - JOUR. T1 - Effect of magnesium on preferential oxidation of carbon monoxide on platinum catalyst in hydrogen-rich stream. AU - Cho, Sung Ho. AU - Park, Jong Soo. AU - Choi, Seung Hoon. AU - Kim, Sung Hyun. PY - 2006/6/1. Y1 - 2006/6/1. N2 - The effects of magnesium on platinum catalyst used for the preferential oxidation of carbon monoxide for polymer electrolyte membrane fuel cell applications are investigated. The CO conversion and selectivity on Pt-Mg/Al2O3 for a H2-rich stream are 93.1 and 62.0%, respectively, but only 70.2 and 46.89% on Pt/Al2O3. The superior activity of Pt-Mg/Al2O3 for the preferential oxidation of CO is due to an increase in the hydroxyl groups that results from an increase in basicity with the addition of Mg, as well as to an increase in the electron density on the surface of the Pt catalyst. Moreover, the content of hydroxyl groups on the Pt catalysts is promoted by water vapour.. AB - The effects of magnesium on platinum catalyst used for the preferential ...
The binding of CO to ascorbate-reduced Pseudomonas cytochrome oxidase was investigated by static-titration, stopped-flow and flash-photolytic techniques. Static-titration data indicated that the binding process was non-stoicheiometric, with a Hill number of 1.44. Stopped-flow kinetics obtained on the binding of CO to reduced Pseudomonas cytochrome oxidase were biphasic in form; the faster rate exhibited a linear dependence on CO concentration with a second-order rate constant of 2 × 10(4) M-1-s-1, whereas the slower reaction rapidly reached a pseudo-first-order rate limit at approx. 1s-1. The relative proportions of the two phases observed in stopped-flow experiments also showed a dependency on CO concentration, the slower phase increasing as the CO concentration decreased. The kinetics of CO recombination after flash-photolytic dissociation of the reduced Pseudomonas cytochrome oxidase-CO complex were also biphasic in character, both phases showing a linear pseudo-first-order rate dependence ...
TY - JOUR. T1 - Luminal and non-luminal non-competitive inhibitor binding sites on the nicotinic acetylcholine receptor (Review). AU - Arias, Hugo R.. PY - 1996/1/1. Y1 - 1996/1/1. N2 - The nicotinic acetylcholine receptor presents two very well differentiated domains for ligand binding that account for different cholinergic properties. In the hydrophilic extracellular region of the a subunit exist the binding sites for agonists such as the neurotransmitter acetylcholine, which upon binding trigger the channel opening, and for competitive antagonists such as d-tubocurarine, which compete for the former inhibiting its pharmacological action. For non-competitive inhibitors, a population of low-affinity binding sites have been found at the lipid-protein interface of the nicotinic acetylcholine receptor. In addition, at the M2 transmembrane domain, several high-affinity binding sites have been found for non-competitive inhibitors such as chlorpromazine, triphenylmethylphosphonium, the local ...
Coartem® is the combination of artemether and lumefantrine used for the treatment of uncomplicated falciparum malaria 1. This oral combination seems to be well-tolerated and is useful for treatment of multi-drug resistant Plasmodium falciparum. This unique anti-malarial agent combines the fast, but short-acting artemether with a less potent, but longer-acting lumefantrine. Original studies with the combination demonstrated safety and efficacy in adults and children with uncomplicated falciparum malaria. 2,3 Additional studies showed superiority with respect to parasite clearance time versus halofantrine,4 chloroquine5, and mefloquine6. Coartem® also demonstrated a faster reduction in parasite burden after 24-hours versus halofantrine4, chloroquine5 (in adults), chloroquine (in children) 7, and mefloquine6. Various other studies have shown artemether-lumefantrine to have a superior 28-day cure rate, as well as time to fever resolution compared to other antimalarial agents.1 Both components of ...
TY - JOUR. T1 - Effects of inorganic anions on Fenton oxidation of organic species in landfill leachate. AU - Deng, Yang. AU - Rosario-Muniz, Edualberto. AU - Ma, Xingmao. PY - 2012/1/1. Y1 - 2012/1/1. N2 - Fenton oxidation typically achieves only a moderate removal efficiency of chemical oxidation demand (COD) in treatment of a landfill leachate, incomparable to some other chemical oxidation processes (e.g. electrochemical oxidation). A traditional viewpoint is that the remaining highly oxidized organic species become recalcitrant to hydroxyl radical (OH·)-induced oxidation at a higher degree of Fenton oxidation. Although this may, at least partially, be true, the effects of inorganic anions, which are abundant in leachate, on Fenton oxidation have been largely ignored. The objective of this study is to assess the roles of three inorganic anions (nitrate, sulfate, and chloride) originally present in or externally added to leachate during Fenton oxidation of refractory organic species in ...
Author Summary The simian parasite Plasmodium knowlesi is a common cause of malaria in Malaysian Borneo; however, little is known about its emergence over time, particularly in Sabah. We reviewed all available Sabah Department of health malaria notification records from 1992-2011, and considered notifications of P. malariae and P. knowlesi as a single group due to their microscopic similarity. We found that malaria notifications in Sabah have decreased dramatically, with P. falciparum and P. vivax notifications peaking at 33,153 and 15,877 respectively during 1994-1995, and falling to 605 and 628 respectively in 2011. Notifications of P. malariae/P. knowlesi fell from a peak of 614 in 1994 to ≈100/year in the late 1990s/early 2000s, however increased |10-fold between 2004 (n = 59) and 2011 (n = 703). In 1992 P. falciparum, P. vivax and P. malariae/P. knowlesi monoinfections accounted for 70%, 24% and 1% respectively of malaria notifications, compared to 30%, 31% and 35% in 2011. The increase in P.
TY - JOUR. T1 - IR spectroscopic investigation of the particle size and morphology of platinum nanoparticles supported on mesoporous silicate. AU - Molnár, É. AU - Konya, Z.. AU - Tasi, Gy. AU - Kiricsi, I.. PY - 2005/1/1. Y1 - 2005/1/1. N2 - Platinum supported on SBA-15 mesoporous silicate was prepared by a two-step procedure. The catalyst was characterized by TEM, XRD, MAS-NMR and IR spectroscopy and BET, TG-DTG measurements. The catalytic activity of the Pt containing silicate was investigated by IR spectroscopy using cyclohexene hydrogenation and dehydrogenation reaction. The changes occurred both in the gas phase and the adsorbed phase were monitored simultaneously. The quantitative analysis of the bands showed that even kinetic experiments could be performed using the set-up reported. We found that the catalytic activity is influenced by the size and shape of the Pt nanoparticles (the smaller the size the higher is the catalytic activity) and the preparation of the catalyst (the highest ...
Bangladesh faces increasing levels of chloroquine resistance, and drug sensitivity to sulfadoxine-pyremethamine is already compromised. Therefore, the Ministry of Health recently changed the national treatment guidelines to artemisinin-based combination therapies. The purpose of this study was to determine the baseline therapeutic efficacy of artemether-lumefantrine used as a six-dose regimen for the treatment of uncomplicated Plasmodium falciparum malaria. Sixty-seven patients were enrolled in the study; the cure rate in a 42-day follow-up after an adjustment by polymerase chain reaction was 94.3%. The treatment led to rapid fever (mean ± SD = 25.82 ± 12.14 hours) and parasite (30.36 ± 19.43 hours) clearance. These data suggest that artemether-lumefantrine is a highly efficacious and well-tolerated treatment for uncomplicated P. falciparum malaria in Bangladesh.
TY - JOUR. T1 - Sonochemical preparation of gold nanoparticles. T2 - Comparison with the thermal reduction system. AU - Shimazaki, Yuzuru. AU - Ando, Chiyoko. AU - Saeki, Shu. AU - Kobayashi, Yoshio. AU - Konno, Mikio. PY - 2007/10/20. Y1 - 2007/10/20. N2 - Comparison was made for the citrate stabilized gold colloids prepared sonochemically and thermally. In the sonochemical reduction system, purge gas had large influence on the formation of gold nanoparticles, while little effect was observed for the thermal reduction system. The average diameter of sonochemically prepared gold nanoparticles was smaller than that of thermally prepared gold nanoparticles when prepared at the same concentrations of HAuCl4 and Na3 citrate. The average diameter of the sonochemically prepared gold nanoparticles was increased with an increase in the HAuCl4 concentration ([Na3 citrate]/[HAuCl4] = 7), while the average diameter of the thermally prepared gold colloid was independent of the HAuCl4 concentration. These ...
In enzymology, a 6,7-dihydropteridine reductase (EC 1.5.1.34) is an enzyme that catalyzes the chemical reaction a 5,6,7,8-tetrahydropteridine + NAD(P)+ ⇌ {\displaystyle \rightleftharpoons } a 6,7-dihydropteridine + NAD(P)H + H+ The 3 substrates of this enzyme are 5,6,7,8-tetrahydropteridine, NAD+, and NADP+, whereas its 4 products are 6,7-dihydropteridine, NADH, NADPH, and H+. This enzyme participates in folate biosynthesis. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5,6,7,8-tetrahydropteridine:NAD(P)+ oxidoreductase. Other names in common use include 6,7-dihydropteridine:NAD(P)H oxidoreductase, DHPR, NAD(P)H:6,7-dihydropteridine oxidoreductase, NADH-dihydropteridine reductase, NADPH-dihydropteridine reductase, NADPH-specific dihydropteridine reductase, dihydropteridine (reduced nicotinamide adenine dinucleotide), reductase, dihydropteridine reductase, ...
The reaction of H2O2 with thioanisole and p-methoxythioanisole catalysed by lignin peroxidase from Phanerochaete chrysosporium has been studied spectrophotometrically under turnover and single turnover conditions with a stopped-flow apparatus. Pre-formed lignin peroxidase compounds I and II are each able to react with the sulphides to form a sulphide radical cation. The radical cation is then converted into the sulphoxide either by reaction with the medium or by reaction with compound II. This is the first report of a direct reaction between compound II and the substrate radical cation. With thioanisole, significant enantiomeric selectivity and high oxygen incorporation in the sulphoxide are obtained because compound II is preferentially reduced by the enzyme-bound thioanisole radical cation compared with the neutral substrate. By contrast, with p-methoxythioanisole, the data imply formation of an intermediate ternary complex comprising compound II, radical cation and neutral substrate, such ...
TY - JOUR. T1 - Nonadditivity of Mutational Effects at the Folate Binding Site of Escherichia coli Dihydrofolate Reductase. AU - Huang, Zheng. AU - Wagner, Carston R.. AU - Benkovic, Stephen J.. PY - 1994/9/1. Y1 - 1994/9/1. N2 - The function of the hydrophobic residues Leu28, Phe31, Ile50, and Leu54 at the folate binding site in Escherichia coli dihydrofolate reductase (5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3) has been studied by a combination of site-specific mutagenesis and reaction kinetics. Studies suggest that the overall protein structure and kinetic sequence for the reaction did not change for the mutant proteins compared to the wild-type enzyme. Two sets of mutated reductases have been constructed. The first set, in which the side chains of the targeted amino acids are spatially well separated (∼8 Å), includes two single mutants (L28Y and L54F) and a double mutant (L28Y-L54F). This set features residues that increased the side chain surface area and the potential ...
A two-site kinetic model with an interaction between two identical binding sites provides an alternative approach to modeling data for those substrates and isoforms exhibiting atypical glucuronidation kinetics (i.e., substrate inhibition or sigmoidal kinetics). For 4MU glucuronidation by UGT2B7 and 1NP glucuronidation by UGT 1A1, 1A6, 1A7, 1A8, 1A9, and 2B7, an interaction between substrate molecules is associated with positive cooperativity and increased binding affinity of the second molecule (α ,1 from fitting to two-site model), an observation that has been reported previously for numerous CYP3A4 substrates (Houston et al., 2003). In addition to the decrease in product formation associated with the substrate inhibition profiles obtained for 4MU and 1NP glucuronidation by UGT1A3 and 4MU glucuronidation by UGT1A8, fitting to the two-site model also indicates an increase in binding affinity (α ,1). Recent work from this laboratory demonstrated that morphine 3- and 6-glucuronidation by UGT2B7 ...
Analysis of volatile compounds from the selected flower buds, grown in -vitro and caUus cultures of Michelia alba D.C were performed using the gas chromatography technique with mass spectrometry detector (GC-MS). The results showed that the major volatile compound obtained from the three-selected tlower bud was dihydrocarveol. Petal grown in-vitro on the Murashige and Skoog (MS) basal medimn with different concentrations of plant growth regulators did not produce any dihydrocarveol. But callus grown in the culture medium containing 1.25 mgIL (w/v) ofNAA plus 1.35 mgIL (w/v) ofBAP (T20) and 0.8 mgIL (w/v) ofNAA plus 1.85 mgIL of BAP (T23) produced linalool as a major compounds. On the other hand, callus treated with 1.25 mgIL (w/v) ofNAA plus 0.45 mgIL (w/v) ofBAP (TIO) and T20 (1.25 mgIL (w/v) of NAA plus 1.35 mgIL (w/v) of BAP were able to synthesis cyclohexane (32.96±1.94%) compared to T23 (17.015±1.06%). Callus derived from flower petal of M alba treated with 1.25 mgIL (w/v) ofNAA plus 0.45 ...
The ionic strength dependence of the reduction of cytochrome c peroxidase compound I by horse cytochrome c has been studied, using stopped-flow technigue, in pH 7.5, potassium phosphate/nitrate buffer. The temperature was set at 25 ± 1° C. The wavelength was monitored at 4 32 nm, an isobestic point for ferri-/ferrocytochrome c, so only the absorbance change of the reduction of cytochrome c peroxidase compound I to compound II can be observed. The observed rate constant, kobs, as a function of the concentration of ferrocytochrome c shows a non-linear increase with increasing ionic strength. A two-parameter eguation is needed to fit the data at low ionic strength, 20 mM to 40 mM, while a three-parameter equation is needed at high ionic strength, 65 mM and above. The maximum rates of these reductions also show two different types of ionic strength dependence. At 20 mM to 40 mM ionic strength, the maximum rate of reduction decreases slightly, within experimental error, with increasing ionic ...
TY - JOUR. T1 - Iron-sulfur centers in the photosynthetic reaction center complex from Chlorobium vibrioforme. Differences from and similarities to the iron-sulfur centers in Photosystem I. AU - Kjær, Bodil. AU - Jung, Yean Sung. AU - Yu, Lian. AU - Golbeck, John H.. AU - Scheller, Henrik Vibe. PY - 1994/7/1. Y1 - 1994/7/1. N2 - The photosynthetic reaction center complex from the green sulfur bacterium Chlorobium vibrioforme has been isolated under anaerobic conditions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals polypeptides with apparent molecular masses of 80, 40, 30, 18, 15, and 9 kDa. The 80- and 18-kDa polypeptides are identified as the reaction center polypeptide and the secondary donor cytochrome c551 encoded by the pscA and pscC genes, respectively. N-terminal amino acid sequences identify the 40-kDa polypeptide as the bacteriochlorophyll a-protein of the baseplate (the Fenna-Matthews-Olson protein) and the 30-kDa polypeptide as the putative 2[4Fe-4S] protein ...
Other names: D. vulgaris str. Hildenborough, Desulfovibrio vulgaris (STRAIN HILDENBOROUGH), Desulfovibrio vulgaris ATCC 29579, Desulfovibrio vulgaris Hildenborough, Desulfovibrio vulgaris str. Hildenborough, Desulfovibrio vulgaris subsp. vulgaris (strain Hildenborough), Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, Desulfovibrio vulgaris subsp. vulgaris str. Hildenborough ...
Objectives: For the purpose of blocking transmission of Plasmodium falciparum malaria from humans to mosquitoes, a single dose of primaquine is recommended by theWHO as an addition to artemisinin combination therapy. Primaquine clears gametocytes but causes dose-dependent haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Evidence is needed to inform the optimal dosing of primaquine for malaria elimination programmes and for the purpose of interrupting the spread of artemisininresistant malaria. This study investigates the efficacy and safety of reducing doses of primaquine for clearance of gametocytes in participants with normal G6PD status. Methods and analysis: In this prospective, fourarmed randomised placebo-controlled double-blinded trial, children aged 1-10 years, weighing over 10 kg, with haemoglobin ≥8 g/dl and uncomplicated P falciparum malaria are treated with artemether lumefantrine and randomised to receive a dose of primaquine (0.1, 0.4 or 0.75 mg ...
TY - JOUR. T1 - pH Dependence of and Kinetic Solvent Isotope Effects on the Methanolysis and Hydrolysis of β-Lactams Catalyzed by Class C β-Lactamase. AU - Page, Michael I.. AU - Vilanova, Bartolomé. AU - Layland, Nicola J.. PY - 1995/12. Y1 - 1995/12. N2 - The methanolysis of benzylpenicillin is catalyzed by Enterobacter cloacae P99 class C β-lactamase and the pH dependence of kcat indicates that the catalytic groups involved of pKa ca. 5 and 10 are the same as those for hydrolysis. The kinetic solvent isotope effect (KSIE) is 1.42 for both the hydrolysis and methanolysis of benzylpenicillin. However, there is an inverse KSIE on of 0.83 ± 0.05 for the hydrolysis of benzylpenicillin and cephaloridine. There is also an abnormally high shift in the low pKa on going from H2O to D2O of 0.85 ± 0.15 from the pH dependence of both kcat and kcat/Km for both methanolysis and hydrolysis. The D2O shift on the high pKa of ca. 10 is the normal value of ca. 0.4. These results are consistent with a ...
Microbially catalyzed oxidation-reduction reactions drive nutrient cycling and energy flux on Earth. Photoautotrophs, which include the cyanobacteria (oxygenic) and purple and green sulfur bacteria (anoxygenic), transform light energy into chemical energy and are responsible for substantial global primary productivity. Anoxygenic phototrophs, in particular, play a crucial role in biogeochemical cycling in anoxic illuminated environments because of their ability to oxidize an array of inorganic compounds for CO2 fixation. Electron donors include molecular hydrogen, nitrite, and reduced sulfur compounds. Recent evidence has also suggested that solid-phase conductive substances (SPCSs), including rust (mixed-valent iron minerals) and their proxies (poised electrodes), can serve as electron donors for anoxygenic phototrophs. This phenomenon is called phototrophic extracellular electron uptake (EEU) and is the reverse process of extracellular electron transfer (EET) performed by metal-reducing bacteria.
Mono- and Stereopictres of 5.0 Angstrom coordination sphere of Copper atom in PDB 2ein: Zinc Ion Binding Structure of Bovine Heart Cytochrome C Oxidase in the Fully Oxidized State
Microbial electron transfer has recently gained considerable attention, as it is fundamental in the development of bioelectrochemical applications for renewable bioenergy and bioremediation of waste. Until now, most attention has been focused on the metal reducing bacteria Shewanella oneidensis and Geobacter sulfurreducens, which are capable of extracellular electron transfer over micrometer distances. Yet large-scale applications of these bioelectrochemical systems are still limited. Due to their capability for long-distance electron transport (LDET; centimeter scale), cable bacteria have emerged as a new and unique opportunity for electromicrobiological research. Recently, cable bacterium filaments have been found attached to the anode of a benthic microbial fuel cell, suggesting they can interact with electrodes and hence may play a potential role in bioelectrochemical systems. Unraveling the electron transfer mechanism of cable bacteria is therefore necessary to see if and how they can be ...
Nanoporous, p-type NiO films were sensitized with coumarin 343 (C343), and the photoinduced electron transfer dynamics was studied in the presence of different concentrations of electrolyte (I-3(-)/I- in propylene carbonate). Electron transfer from the valence band of NiO to the excited C343 is very fast, occurring on time scales from hundreds of femtoseconds to a few picoseconds, but also the subsequent recombination is quite rapid, on the time scale of tens of picoseconds. Nevertheless, formation of an intermediate, attributed to I2-I NiO(+), was observed on the picosecond time scale. Simultaneously the reduced dye was converted back to the C343 ground state, indicating that recombination could be intercepted by 13 reduction. Consistent with that interpretation, we observed oxidized NiO and depletion Of 13 persisting on the millisecond time scale. Complete dye-sensitized solar cells (DSSCs) with these films as photocathode gave up to 10-11% incident photon to current conversion efficiency at ...
Emma Watsons legal team sent a cease and desist letter, along with the description of a nasty lawsuit to celeb tabloid site Celeb Jihad for posting a racy nude photo, that was not supposed to hit the web.. According to the letter obtained by TMZ, the photos were taken by Emmas stylist, who then gave Emma all rights to the photo.. After investigating the site, about 90% of the sites content is fake, including all fake comments by popular commenting system Disqus. They basically Photoshop celebrity heads on other already naked women, including editing porn videos to appear to be famous celebrities. We found out the site has been threatened with lawsuits about a gazillion times, with the most popular one back in the day by Taylor Swift for posting fake nude photos with Taylors head using Photoshop.. The one thing we and other legitimate celebrity reporting sites can not understand, is Googles love for the site in their search engine. For several years now if you search for any type of nude ...
Photosystem II (PSII) is a light-driven water: plastoquinone oxidoreductase that uses light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation. It consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The D1/D2 (PsbA/PsbA) reaction center heterodimer binds P680, the primary electron donor of PSII as well as several subsequent electron acceptors. D2 is needed for assembly of a stable PSII complex.
TY - JOUR. T1 - Comparison of colorimetric and membrane introduction mass spectrometry techniques for chloramine analysis. AU - Lee, Wontae. AU - Westerhoff, Paul. AU - Yang, Xin. AU - Shang, Chii. PY - 2007/7. Y1 - 2007/7. N2 - Three methods for the determination of chloramines in water were compared using pH-buffered nanopure water and natural organic matter (NOM) solutions. We investigated whether the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method and/or an adapted indophenol method (Hach MonochlorF) are suitable for determining the concentration of monochloramine in drinking water. Membrane introduction mass spectrometry (MIMS) was used as a reference analysis method to determine the different chloramine species in water. All methods measured monochloramine accurately in Nanopure water, but the DPD colorimetric method measured higher residuals (inorganic and organic chloramines) than MonochlorF or MIMS when in the presence of NOM due to organic chloramines. The indophenol method ...
Release date: May 22, 2012. Pages: 336. Summary: While vacationing in Florida, Emma bumps into Galen and his sister Rayna. Emma doesnt know it yet, but Galen and Rayna are royal Syrena-merpeople. Their kingdom is going through a rough patch, and Emma might have a gift special enough to fix it. This is when Emma discovers that she isnt who she thought she was-shes not even human.. My thoughts: Of Poseidon is one of those rare books with which I find myself torn. Part of me loves the silliness of it, and for the sake of pure enjoyment, Of Poseidon delivers. On the other hand, it could have been so much more. The story is riddled with clichés, such as a love interest whose sole purpose in life is to protect and assist the heroine. There is instantaneous romance. But during the first few chapters of the book, I still found myself smiling. Anna Banks writing style is compulsively readable, and the personality she gives to Emma is for the most part fun. If you go into Of Poseidon expecting a few ...
Platinum has been established as the most powerful electrocatalyst for the 4-electron reduction of oxygen to water in acid medium in a conventional fuel cell. The reaction becomes less efficient and its efficiency suffers from the formation of the hydrogen peroxide intermediate at lower Pt loadings or at higher current densities. Recent progress in the area concerns fabrication of electrocatalysts in a form of carbon-supported platinum nanoparticles assembled within organized multilayers or inks deposited on a proton-conducting membrane. Important issues include the stabilization of Pt nanoparticles (to prevent their agglomeration causing decrease of the active surface area), the enhancement of their reactivity (e.g. by modification of their surfaces or by formation of novel bimetallic systems), the interfacial protection of nanostructured Pt from poisoning (e.g. by the development of methanol or CO tolerant systems using Ru-Se nanoparticles), and the activation of metal nanoparticles through ...
A lot of people have spent a lot of time studying the properties of gold and platinum nanoparticles that are used to catalyze the reaction of carbon monoxide with water to make hydrogen and carbon dioxide," said Maria Flytzani-Stephanopoulos, professor of chemical and biological engineering at Tufts and the lead researcher of the project. "We find that for this reaction over a cerium oxide catalyst carrying the gold or platinum, metal nanoparticles are not important. Only a tiny amount of the precious metal in non metallic form is needed to create the active catalyst. Our finding will help researchers find a cost-effective way to produce clean energy from fuel cells in the near future". She and her two colleagues, doctoral student Qi Fu and research professor Howard Saltsburg, were funded by a $300,000 three-year grant from the National Science Foundation, and have filed a provisional patent for their research. Their cutting-edge work in catalytic fuel processing to generate hydrogen for fuel ...