Common reaction mechanisms

This study synthesizes the use of chemicals to prevent one of common concrete durability problems, alkali-silica reaction (ASR), and can help researchers (i) identify widely used potential chemicals and evaluate these chemical solutions to prevent ASR with proper understanding of mechanisms, and (ii) to identify the research gaps in order to develop guidelines and implementation plan on the use of these chemicals for future research.

8p tohitohi 19-05-2020 18 1   Download

We have analyzed several mathematical models that describe inhibition of the factor VIIa–tissue factor complex (VIIa–TF) by tissue factor pathway inhibitor (TFPI). At the core of these models is a common mechanism of TFPI action suggesting that only the Xa–TFPI complex is the inhibitor of the extrinsic tenase activity. However, the model based on this hypothesis could not explain well all the available experimental data. Here, we show that a good quantitative description of all experimental data could be achieved in a model that contains two more assumptions....

16p research12 01-06-2013 35 5   Download

DNA ligases are the enzymes responsible for the repair of single-strandedanddouble-strandednicks indsDNA.DNA ligases are structurally similar, possibly sharing a common molecular mechanism of nick recognition and ligation catalysis. This mechanism remains unclear, in part because the structure of ligase in complex with dsDNAhas yet to be solved.DNA ligases share common structural elementswith DNA polymerases, which have been cocrystallized with dsDNA. Based on the observed DNA polymerase–dsDNA interactions, we propose a mechanism for recognition of a single-stranded nick by DNA ligase....

7p tumor12 22-04-2013 37 1   Download

Ferredoxin (flavodoxin)-NADP(H) reductases (FNR) are ubiquitous flavoenzymes that deliver NADPH or low potential one-electron donors (ferredoxin, flavodoxin) to redox-based metabolisms in plastids, mitochondria and bacteria. The plant-type reductase is also the basic prototype for one of the major families of flavin-containing electron transferases that display common functional and structural properties.

16p fptmusic 16-04-2013 37 1   Download

Ketol-acid reductoisomerase (EC 1.1.1.86) is involved in the biosynthesis of the branched-chain amino acids. It is a bifunctional enzyme that cata-lyzes two quite different reactions at a common active site; an isomeriza-tion consisting of an alkyl migration, followed by an NADPH-dependent reduction of a 2-ketoacid. The 2-ketoacid formed by the alkyl migration is not released. Using the pure recombinant Escherichia colienzyme, we show that the isomerization reaction has a highly unfavourable equili-brium constant....

0p awards 05-04-2013 61 1   Download

Aspergillus nigerisopullulanase (IPU) is the only pullulan-hydrolase inglycosyl hydrolase (GH) family 49 anddoes not hydrolyse dextran at all, while all other GH family 49 enzymes are dextran-hydrolysing enzymes. To investigate the common catalyticmechanismofGHfamily 49 enzymes, nine mutants were prepared to replace residues conserved among GH family 49 (four Trp, three Asp and two Glu).

8p awards 05-04-2013 46 3   Download

The conformationally coupled mechanism by which ATP is utilized by yeast Hsp90 is now well characterized. In contrast, ATP utilization by human Hsp90s is less well studied, and appears to operate differently. To resolve these conflicting models, we have conducted a side-by-side biochem-ical analysis in a series of mutant yeast and human Hsp90s that have been both mechanistically and structurally characterized with regard to the crys-tal structure of the yeast Hsp90 protein.

11p vinaphone15 27-02-2013 40 1   Download

Adverse Reactions Adverse drug reactions are frequently classified by mechanism as either dose-related ("toxic") or unpredictable. Unpredictable reactions are either idiosyncratic or allergic. Dose-related reactions include aminoglycoside-induced nephrotoxicity, linezolid-induced thrombocytopenia, penicillin-induced seizures, and vancomycin-induced anaphylactoid reactions. Many of these reactions can be avoided by reducing dosage in patients with impaired renal function, limiting the duration of therapy, or reducing the rate of administration.

9p colgate_colgate 21-12-2010 61 3   Download

Polymorphous Light Eruption After sunburn, the most common type of photosensitivity disease is polymorphous light eruption (PLE), the mechanism of which is unknown. Many affected individuals never seek medical attention because the condition is often transient, becoming manifest each spring with initial sun exposure but then subsiding spontaneously with continuing exposure, a phenomenon known as "hardening.

5p konheokonmummim 03-12-2010 68 2   Download

Delayed hypersensitivity mechanisms directed by drug-specific T cells are probably the most important mechanisms in the etiology of the most common drug eruptions—morbilliform exanthems—and also of rare and severe forms such as hypersensitivity syndrome, acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Drugspecific T cells have been detected in these types of drug eruptions. Contrary to what has been believed for years, the antigen is more often the native drug itself than its metabolites.

5p konheokonmummim 03-12-2010 82 5   Download

Reaction mechanism: the description of the step-by-step process by which reactants are changed / converted into products. A nucleophile: an electron-rich species that can form a covalent bond by donating 2 electrons to a positive center.

62p 3dagkhoa 28-10-2010 139 32   Download

Limitations: The Wurtz reaction is limited to the synthesis of symmetric alkanes from alkyl iodides & bromides. If two dissimilar alkyl halides are taken as reactants, then the product is a mixture of alkanes that is, often, difficult to separate. A side reaction also occurs to produce an alkene. The side reaction becomes more significant when the alkyl halides are bulky at the halogen-attached carbon.

25p 3dagkhoa 13-10-2010 169 10   Download