Hydrolases esterases

Esterase ESI5 Acylcarnitine hydrolase Carboxylesterase RL2 Esterase pi 5.5 Hydrolase pi 5.6 Acylcarnitine hydrolase Esterase Esterase I Esterase ES10 Carboxylesterase RH1 Octanoylglycerol lipase Esterase pi 6.1 Hydrolase pi 6.2... 

Many enzymes are not exactly substrate-specific, e.g. peptidases acting as hydrolases, esterases etc. to some extent (Vallee and Williams 1968) or vice versa. 

Hydrolases Esterases Glycosidases Peptidses Phosphatases Thiolases Phospholipases Amidases Cleavage of bonds by hydrolysis A-B+ H2O A-H +B-OH... 

In such coupled systems, care must be taken in choosing reaction conditions, such that the enzyme of interest is catalyzing the rate-determining step. Special synthetic colorless substrates converted to colored products have been developed for hydrolases (esterases, phosphatases, glycosidases and proteases) 4-nitrophenol or 4-ni-troanilide are used as the alcohol or amide component, which can be measured readily around 400-420 nm. 

Numerous biochemical reactions directly affecting pesticides have been described using pure cultures of bacteria. Enzymes which catalyze the conversion of pesticides tend to fall into two classes hydrolases (esterases, amldases, halldohydrolases) and oxygenases (mono or dioxygenases). 

Xanthin oxidase (XO) Flavin-containing monooxygenase (FMO) Monoamine oxidase (MO) Aldehyde dehydrogenase CYP reductase Carbonyl reductase Epoxide hydrolase Esterases... 

Nonspecific hydrolases Esterases Phosphatases Fluorescein diacetate Nitrophenylphosphate Fluorescein diacetate MUF-phosphate... 

Although cyanohydrins are accessible with high enantiomeric purity via the above described oxynitrilase-catalyzed reactions, the resulting products are rather unstable with a tendency to racemization via their equilibrium with HCN and corresponding aldehydes. In contrast, enantiomerically pure cyanohydrin derivatives such as acetates are chemically quite stable also toward racemization. Therefore, bacterial ester hydrolases (esterases and lipases), which are well known for then capability of enantiomer differentiation in racemic esters and in particular commercially available lipases from Pseudomonas sp. (Amano, Japan), were employed for the preparation of enantiomerically pure cyanohydrin esters. 

Hydrolases. Enzymes catalysing the hydrolytic cleavage ofC —O, C —N and C —C bonds. The systematic name always includes hydrolase but the recommended name is often formed by the addition of ase to the substrate. Examples are esterases, glucosidases, peptidases, proteinases, phospholipases. Other bonds may be cleaved besides those cited, e.g. during the action of sulphatases and phosphatases. 

The principal methods for the hydrolase-promoted synthesis of enantiomerically pure alcohols are depicted in Figure 6.44. Biocatalytic acylation and alcoholysis have been reviewed recently [116,117]. Lipases, esterases, and proteases catalyze these reactions, but CAL-B [118-120], CRL [121,122], and diverse lipase preparations from Pseudomonas species are common place. 

Enzymes catalyzing the hydrolysis of esters are termed esterases. They belong to a larger group of enzymes termed hydrolases, which can cleave a variety of chemical bonds by hydrolytic attack. In the classification of hydrolases of the International Union of Biochemistry (lUB), the following categories are recognized ... 

The microsomal fraction consists mainly of vesicles (microsomes) derived from the endoplasmic reticulum (smooth and rough). It contains cytochrome P450 and NADPH/cytochrome P450 reductase (collectively the microsomal monooxygenase system), carboxylesterases, A-esterases, epoxide hydrolases, glucuronyl transferases, and other enzymes that metabolize xenobiotics. The 105,000 g supernatant contains soluble enzymes such as glutathione-5-trans-ferases, sulfotransferases, and certain esterases. The 11,000 g supernatant contains all of the types of enzyme listed earlier. 

Emphasis is given to the critical role of metabolism, both detoxication and activation, in determining toxicity. The principal enzymes involved are described, including monooxygenases, esterases, epoxide hydrolases, glutathione-5 -transferases, and glucuronyl transferases. Attention is given to the influence of enzyme induction and enzyme inhibition on toxicity. 

Hydrolases lipase, protease, esterase nitrilase, nitrile hydratase glycosidase, phosphatase hydrolysis reactions in H20... 

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