Reductive enzymatic

NADH reaction, 46 526 nitrogen complexes, 46 505-506 oxidation, 46 511-519 reduction, enzymatic, 46 524-525 reduction, nonenzymatic, 46 525-526 small ligands, 46 506-507 Fe(IV)=0... 

For the mutagenicity testing of azo dyes the Prival test, a modification of the Ames test, was found to be superior. The reductive enzymatic cleavage of the azo bond occuring in mammals is simulated by this test. 

The enantioselective synthesis of 1 has also been achieved by a number of methods including enzymatic resolution of a keto ester precursor to the racemate followed by conversion of the ester to an amino group, enzymatic resolution of an amino azide precursor followed by reduction, enzymatic resolution through 0-acylation of a racemic A -benzylcarbamate derivative of and the resolution via the formation of an amide with a homochiral amino acid. Bioconversion of in-... 

To determine the stereoselectivity of diastereotopic proton abstraction from the Pro-R methylene group of ACPC (9) in the fragmentation (occurring between Pro-S p-C and a-C), 2-ethyl-[3-Di]-ACPC (8a) was prepared with the ethyl side chain and deuterium substituent in cis relationship. Incubation of this compound followed by in situ reductive enzymatic trapping with (25)-lactate dehydrogenase yielded 2-hydroxy-[3-D]-hexanoate where the R,5-placement of D was analyzed by NMR and the D-content by mass spectrometry. These results had defined the stereoselectivity for )5-H-abstraction from the Pro-R methylene of 2-ethyl-ACPC (8) as the proton removal in the overall fragmentation process and by analogy the same in ACPC (9). These results place stereochemical constraints on the ACPC deaminase process and were accommodated in Scheme 10. 

Hydrogen peroxide Lens care solutions Dialysis UV-Vis Up to 342 mg L 1 Sequential injection lab-on-valve system low dialysis efficiency (1.25 %) to promote in-line dilution, thus sensitivity reduction enzymatic assay [60]... 

Copper is an essential element. It is of a great importance in the metabolic processes of plants, its content in plant tissues being very low, much lower than those of zinc and manganese. Copper ions form complexes with proteins and with the other biopolymers in plant tissues. These complexes are more stable than those of the other metals. Binding to proteins enhances the catalytic activity of copper. Copper participates in many oxidation-reduction enzymatic systems, and it is thus of importance particularly in respiration and photosynthesis processes. In plants it is also essential in the nitrogen metabolism. Its concentration in plants ranges... 

Sugars A wide range of methods is available for the determination of sugars in fruit and fruit products. These include relatively simple refractometry and hydrometry techniques, polarimetry, copper(II) reduction, enzymatic/color detection, and various chromatographic techniques. These vary greatly in their sensitivity, specificity, and in the level of equipment and expertise required, and these considerations generally dictate the method chosen. 

Subsequent research on osmium-modified polymers has shown how the redox potential can be controlled by altering bipyridine ligands of the immobilized osmium complexes. The ability to reliably modulate redox potential has significantly broadened the range of enzymes with which osmium redox polymer are compatible and allows for mediation of oxidative enzymatic reactions as well as reductive enzymatic reactions. 

The conventional electrochemical reduction of carbon dioxide tends to give formic acid as the major product, which can be obtained with a 90% current efficiency using, for example, indium, tin, or mercury cathodes. Being able to convert CO2 initially to formates or formaldehyde is in itself significant. In our direct oxidation liquid feed fuel cell, varied oxygenates such as formaldehyde, formic acid and methyl formate, dimethoxymethane, trimethoxymethane, trioxane, and dimethyl carbonate are all useful fuels. At the same time, they can also be readily reduced further to methyl alcohol by varied chemical or enzymatic processes. 

The product of this reaction 3 hydroxy 3 methylglutaryl coenzyme A (HMG CoA) has the carbon skeleton of mevalonic acid and is converted to it by enzymatic reduction... 

Chemical Properties. Lignin is subject to oxidation, reduction, discoloration, hydrolysis, and other chemical and enzymatic reactions. Many ate briefly described elsewhere (51). Key to these reactions is the ability of the phenolic hydroxyl groups of lignin to participate in the formation of reactive intermediates, eg, phenoxy radical (4), quinonemethide (5), and phenoxy anion (6) ... 

Reductive reactions typically occur in anaerobic environments where there is an abundant supply of electron donors. Electron donors are typically of microbial origin, eg, porphyrins or cysteine, which sometimes leads to confusion regarding the nature, ie, chemical vs enzymatic, of the reductive reaction. By definition, all reductive reactions which are not enzymatically catalyzed are chemical. The most significant chemical reductive reaction is reductive dechlorination. 

The reductive dechlorination of chlorinated aromatics is more compHcated in that the initial dechlorination of more highly chlorinated compounds may be either chemical or enzymatic, eg, PGP, whereas the dechlorination of less chlorinated compounds or dechlorinated products is typically enzymatic. For example, the first dechlorination of 2,4-dichlorophenol (ortho position) can occur either chemically or enzymatically the second dechlorination (para position) is enzymatic (eq. 10). 

An enzymatic assay can also be used for detecting anatoxin-a(s). " This toxin inhibits acetylcholinesterase, which can be measured by a colorimetric reaction, i.e. reaction of the acetyl group, liberated enzymatically from acetylcholine, with dithiobisnitrobenzoic acid. The assay is performed in microtitre plates, and the presence of toxin detected by a reduction in absorbance at 410 nm when read in a plate reader in kinetic mode over a 5 minute period. The assay is not specific for anatoxin-a(s) since it responds to other acetylcholinesterase inhibitors, e.g. organophosphoriis pesticides, and would need to be followed by confirmatory tests for the cyanobacterial toxin. 

Reaction of an achiral reagent with a molecule exhibiting enantiotopic faces will produce equal quantities of enantiomers, and a racemic mixture will result. The achiral reagent sodium borodeuteride, for example, will produce racemic l-deM/eno-ethanol. Chiral reagent can discriminate between the prochiral faces, and the reaction will be enantioselective. Enzymatic reduction of acetaldehyde- -[Pg.106]

Hydrolytic reactions can also be performed at the start as well as oxidative and reductive ones They can be earned out by wet chemistry or enzymatically Examples are listed in Table 11... 

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