The Catalytic Mechanism of Microsomal Epoxide Hydrolase Involves Reversible Formation and Rate-Limiting Hydrolysis of the Alkyl−Enzyme Intermediate

1996 ◽  
Vol 118 (39) ◽  
pp. 9436-9437 ◽  
Author(s):  
Huey-Fen Tzeng ◽  
L. Timothy Laughlin ◽  
Sue Lin ◽  
Richard N. Armstrong
Keyword(s):  
Epoxide Hydrolase ◽  
Catalytic Mechanism ◽  
Microsomal Epoxide Hydrolase ◽  
Reversible Formation ◽  
Rate Limiting ◽  
Hydrolysis Of ◽  
Enzyme Intermediate

Enantioselectivity of the microsomal epoxide hydrolase-catalyzed hydrolysis of trans-4,5-dimethyl-1,2-epoxycyclohexane

1985 ◽  
Vol 50 (9) ◽  
pp. 1471-1474 ◽  
Author(s):  
Giuseppe Bellucci ◽  
Giancarlo Berti ◽  
Maria Ferretti ◽  
Ettore Mastrorilli ◽  
Luca Silvestri
Keyword(s):  
Epoxide Hydrolase ◽  
Microsomal Epoxide Hydrolase ◽  
Hydrolysis Of

scholarly journals The action of cytoplasmic aldehyde dehydrogenase on methyl p-nitrophenyl carbonate and p-nitrophenyl dimethylcarbamate

1989 ◽  
Vol 257 (2) ◽  
pp. 579-584 ◽  
Author(s):  
T M Kitson
Keyword(s):  
Aldehyde Dehydrogenase ◽  
Chloral Hydrate ◽  
Slow Release ◽  
Cysteine Residue ◽  
Single Type ◽  
Rate Of Hydrolysis ◽  
Rate Limiting ◽  
Hydrolysis Of ◽  
Enzyme Intermediate ◽  
Esterase Activities

Cytoplasmic aldehyde dehydrogenase catalyses the hydrolysis of methyl p-nitrophenyl (PNP) carbonate at an appreciable rate that is markedly stimualted by NAD+ or NADH. The nuleotides accelerate the rate-limiting hydrolysis of the acyl-enzyme intermediate while slowing the observed burst of p-nitrophenoxide production. With PNP dimethylcarbamate the enzyme catalyses the slow release of approx. 1 molecule of p-nitrophenoxide per tetrameric enzyme molecule; during the reaction the enzyme becomes effectively inactivated, as the rate of hydrolysis of the acyl-enzyme is virtually zero. The presence of NAD+, NADH, propionaldehyde, chloral hydrate, diethylstilboestrol or disulfiram slows the reaction of enzyme with PNP dimethylcarbamate. The reaction appears to be dependent on a group of pKa 7.6, possibly a cysteine residue. The effect of PNP dimethylcarbamate on the dehydrogenase activity of the enzyme is consistent with there being a single type of active site for the enzyme's dehydrogenase and esterase activities. Steric and electronic factors that govern reaction of the enzyme with PNP substrates are discussed.

Induction of rat liver microsomal epoxide hydrolase by thiazole and pyrazine: hydrolysis of 2-cyanoethylene oxide

1993 ◽  
Vol 14 (8) ◽  
pp. 1665-1670 ◽  
Author(s):  
Sang Geon Kim ◽  
Gregory L. Kedderis ◽  
Renu Batra ◽  
Raymond F. Novak
Keyword(s):  
Rat Liver ◽  
Epoxide Hydrolase ◽  
Microsomal Epoxide Hydrolase ◽  
Hydrolysis Of
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