Biomaterial Database

Effect of alcohols on the hydrolysis catalyzed by human pancreatic carboxylic-ester hydrolase. 1981

D Lombardo, and O Guy

Transfer reactions catalyzed by human pancreatic carboxylic-ester hydrolase (EC 3.1.1.1) were studied in the presence of methanol and butanol as nucleophiles. The addition of alcohols produced an increase in the total rate of 4-nitrophenyl acetate and n-propylthiol acetate disappearance and a concomitant slow decrease of the hydrolysis rate. These results indicate a competitive partitioning of an acyl-enzyme intermediate between water and nucleophile. Moreover, a strong inhibition of the rates of hydrolysis of methyl butyrate and triacetin by nucleophiles is in agreement with a rate-limiting acylation step. The kinetic data and a trans-ester characterization argue in favor of the formation of an acyl-enzyme intermediate and a two-step reaction mechanism, acylation and deacylation both being rate-limiting. The experiments performed with 4-nitrophenyl acetate show the existence of a nucleophile binding site.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D010179	Pancreas	A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.
D010189	Pancreatic Juice	The fluid containing digestive enzymes secreted by the pancreas in response to food in the duodenum.	Juice, Pancreatic,Juices, Pancreatic,Pancreatic Juices
D002265	Carboxylic Ester Hydrolases	Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.	Carboxylesterases,Ester Hydrolases, Carboxylic,Hydrolases, Carboxylic Ester
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000432	Methanol	A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.	Alcohol, Methyl,Carbinol,Sodium Methoxide,Wood Alcohol,Alcohol, Wood,Methoxide, Sodium,Methyl Alcohol
D000440	Butanols	Isomeric forms and derivatives of butanol (C4H9OH).	Alcohols, Butyl,Butanol,Butylhydroxides,Hydroxybutanes,Butyl Alcohols
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities
D043182	Carboxylesterase	Carboxylesterase is a serine-dependent esterase with wide substrate specificity. The enzyme is involved in the detoxification of XENOBIOTICS and the activation of ester and of amide PRODRUGS.	Ali-esterase,B-esterase,CAP-hydrolyzing Enzyme,Capsaicin-Hydrolyzing Enzyme,Carboxyesterase,Carboxylate Esterase,Carboxylester Lipase,Carboxylesterase B,Carboxylic Ester Hydrolase,Esterase 10,Esterase 13,Esterase 3,Esterase 6A,Esterase 8,Esterase ES-1A,Hydrolase S,Isocarboxazid amidase,Naproxen Esterase,Non-specific Carboxylesterase,Non-specific Esterase,Nonspecific Esterase,Procaine Esterase,Ali esterase,B esterase,CAP hydrolyzing Enzyme,Capsaicin Hydrolyzing Enzyme,Carboxylesterase, Non-specific,ES-1A, Esterase,Enzyme, CAP-hydrolyzing,Enzyme, Capsaicin-Hydrolyzing,Ester Hydrolase, Carboxylic,Esterase ES 1A,Esterase, Carboxylate,Esterase, Naproxen,Esterase, Non-specific,Esterase, Nonspecific,Esterase, Procaine,Hydrolase, Carboxylic Ester,Lipase, Carboxylester,Non specific Carboxylesterase,Non specific Esterase,amidase, Isocarboxazid