Esterases catalyzed hydrolyses

L. K. P. Lam, J. B. Jones, Enzymes in Organic Synthesis. 43. Investigation of the Preferred Orientation of Ester Groups in Pig Liver Esterase Catalyzed Hydrolyses Using Conformationally Rigid Substrates , J. Org. Chem. 1988, 53, 2637 - 2639. 

H. J. Gais, G. Btilow, A. Zatorski, M. Jentsch, P. Maidonis, H. Hemmerle, Enzyme-Catalyzed Asymmetric Synthesis. 8. Enantioselectivity of Pig Liver Esterase Catalyzed Hydrolyses of 4-Substituted meso Cyclopentane 1,2-Diesters , /. Org. Chem. 1989,54,5115 - 5122. 

J. B. Jones, R. S. Hinks, P. G. Hultin, Enzymes in Organic Synthesis. 33. Stereoselective Pig Liver Esterase-Catalyzed Hydrolyses of meso Cyclopentyl-, Tetrahydrofuranyl-, and Tetrahydrothiophenyl-1,3-Diesters , Can. J. Chem. 1985, 63, 452-456. 

Acetylcholine esterase-catalyzed hydrolyses have been reported only for a small number of prochiral diacetates (Table 11.1-8). However, several of secondary monoacetates, which are valuable synthetic building blocks, have been obtained with high enantioselectivity (2-6 and 11) by using this enzyme. Acetylcholine esterase should be considered for the hydrolysis of diacetates which are not substrates for lipases and pig liver esterase. 

The Candida cylindracea lipase-catalyzed, Candida rugosa lipase-catalyzed and cholesterol esterase-catalyzed hydrolyses of acetates 88b-102b are examples of the utilization of a remote phenolic ester group as the site of enzymatic attack. For such cases, cholesterol esterase seems to be particularly well suited. 

Hultin, P C., Mueseler, F.)., and Jones, ).B. (1991) Enzymes in organic synthesis. 48. Pig liver esterase and porcine pancreatic lipase catalyzed hydrolyses of 3,4-(isopropylidenedioxy)-2,5-tetrahydrofuranyl diesters. J. Org. Chem., 56 (18), 5375-5380. 

Carboxylesterases and amidases catalyze hydrolysis of carboxy esters and carboxy amides to the corresponding carboxylic acids and alcohols or amines. In general those enzymes capable of catalyzing hydrolysis of carboxy esters are also amidases, and vice versa (110). The role of these enzymes in metabolsim of drugs and insecticides has been reviewed (111, 112). In addition to the interest in mammalian metabolism of drugs and environmental chemicals, microbial esterases have been used for enantioselective hydrolyses (113, 114). 

Hydrolyses Esters and Amides. The plasma, liver, kidney, and intestines contain a wide variety of nonspecific amidases and esterases. These catalyze the metabolism of esters and amides, ultimately leading to the formation of amines, alcohols, and carboxylic acids. Kinetically, amide hydrolysis is much slower than ester hydrolysis. These hydrolyses may exhibit stereoselectivity. 

Enantioselective enzymatic ester hydrolyses of prochiral trimethylsilyl-substituted diesters of the malonate type have been applied for the synthesis of the related optically active monoesters68. As an example of this particular type of biotransformation, the enantioselective conversion of the diester 82 is illustrated in Scheme 17. Hydrolysis of compound 82 in phosphate buffer, catalyzed by porcine liver esterase (PLE E.C. 3.1.1.1) or horse liver acetonic powder (HLAP), gave the optically active monoester 83 (absolute configuration not reported) in 86% and 49% yield, respectively. The enantiomeric purities... 

Some other reactions, such as aldehyde hydration (29) and e ter hydrolyses (30—33) are also catalyzed by the enzyme, but much j ess efficiently than the reversible hydration of CO 2. The esterase reaction, in particular, has been very useful in the kinetic analysis of carbonic anhydrase function, however. 

Acyl Cholinesterases. Acetylcholinesterase (AChE EC 3.1.1.7 CAS 9000-81-1) is the serine esterase which catalyzes the hydrolysis of acetylcholine and possesses an esteratic site, and which is responsible for unspecific hydrolyses of several substrates. Also, butyrylcholinesterase (EC 3.1.1.8 CAS 9001-08-5) has been sometimes used for asymmetric hydrolysis of esters. Acetylcholinesterase has been used for... 

Hydrolyses of esters or amides are common reactions catalyzed by ubiquitous esterases, amidases, and... 

Currently there is considerable interest in developing artificial esterases and peptidases that hydrolyse esters and amides. The first nonenzymatic, catalytic hydrolysis of methyl acetate and acetylcholine in neutral water at 25 has now been described. The complex [Co(trpn)(OH)(OH2)] (10) catalyzes the hydrolysis of methyl acetate at pH 7.6. The reaction is believed to involve the steps shown... 

Cutin and cutin hydrolysate induced the production of very small quantities of a nonspecific esterase which catalyzed the hydrolysis of a variety of small esters but not the hydrolysis of cutin. The following experimental evidence suggests that this protein might be procutinase which reaches the medium in extremely small quantities, probably as a result of a leak in the processing of the precursor (Kolattukudy, 1977b). (1) Like cutinase, the esterase contains an active serine which is involved in catalysis (Purdy and... 

The hydrolysis of bis(pivaloyloxymethyl) AZT 5 -monophosphate (44, Nu = 5 -AZT) has also been evaluated [61], In culture medium containing 10% foetal calf serum and in CEM-cell extract, the triester hydrolyzes to the diester with half-lives of 170 and 30 min, respectively, supporting intracellular release of the diester by esterase catalysis. Under the same conditions, the diester hydrolyses to AZT 5 -monophosphate with half-lives of 30 and 133 min. Anions are typically poor substrates for esterases, and therefore similar rates of hydrolysis for the triester and diester suggests that hydrolysis of the diester is catalyzed by phosphodiesterase. 

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