Ester hydrolases

According to the IUPAC-IUB Enzyme Nomenclature,11 pectinesterase belongs to the carboxyl ester hydrolases (EC 3.1.1.11) and has the systematic name pectin pectyl-hydrolase. The literature also contains the expressions pectin methylesterase, pectin demethoxylase, and pectin methoxylase for the same enzyme. The old name pectase,... [Pg.324]

A few enzymes, such as the previously mentioned CNP, are believed to be fairly specific for myelin/oligodendro-cytes. There is much more in the CNS than in peripheral nerve, suggesting some function more specialized to the CNS. In addition, a unique pH 7.2 cholesterol ester hydrolase is also enriched in myelin. On the other hand, there are many enzymes that are not myelin-specific but appear to be intrinsic to myelin and not contaminants. These include cAMP-stimulated kinase, calcium/calmodulin-dependent kinase, protein kinase C, a neutral protease activity and phosphoprotein phosphatases. The protein kinase C and phosphatase activities are presumed to be responsible for the rapid turnover of MBP phosphate groups, and the PLP acylation enzyme activity is also intrinsic to myelin. [Pg.66]

Mercier, M., G. Pascal, and V. Azais-Braesco. 1990. Retinyl ester hydrolase and Vitamin A status in rats treated with 3,3, 4,4 -tetrachlorobiphenyl. Biochim. Biophys. Acta 1047 70-76. [Pg.1333]

The chemical methods for the quantitation of cholesterol measure total cholesterol, i.e. free and esterified, and so a digitonin precipitate must be prepared if free cholesterol is to be measured. Enzymic methods do not measure the esters and a hydrolysis stage, either chemical or enzymic (using cholesterol ester hydrolase, EC 3.1.1.13), is necessary for the measurement of total cholesterol. [Pg.425]

A selection of carboxylic ester hydrolases (EC 3.1.1) of major or more-modest significance in xenobiotic metabolism is given in Table 2.5. The recommendations of the Enzyme Nomenclature Committee on the classification of esterases cannot be considered completely satisfactory, but, even after decades of debate, a more satisfactory classification system remains to be proposed [56] [57], The main difficulties with esterase classification have been summarized as follows [58],... [Pg.43]

Table 2.5. A Selection of Carboxylic Ester Hydrolases (EC 3.1.1) Having Some Role in Xenobiotic Metabolism ... [Pg.44]

Carboxylesterase Carboxylic ester hydrolase, nonspecific carboxylesterase, ali-esterase, B-esterase Aliphatic esters... [Pg.44]

Arylesterase Aryl-ester hydrolase, A-esterase Aromatic esters... [Pg.44]

The overall metabolism of vitamin A in the body is regulated by esterases. Dietary retinyl esters are hydrolyzed enzymatically in the intestinal lumen, and free retinol enters the enterocyte, where it is re-esterified. The resulting esters are then packed into chylomicrons delivered via the lymphatic system to the liver, where they are again hydrolyzed and re-esterified for storage. Prior to mobilization from the liver, the retinyl esters are hydrolyzed, and free retinol is complexed with the retinol-binding protein for secretion from the liver [101]. Different esterases are involved in this sequence. Hydrolysis of dietary retinyl esters in the lumen is catalyzed by pancreatic sterol esterase (steryl-ester acylhydrolase, cholesterol esterase, EC 3.1.1.13) [102], A bile salt independent retinyl-palmitate esterase (EC 3.1.1.21) located in the liver cell plasma hydrolyzes retinyl esters delivered to the liver by chylomicrons. Another neutral retinyl ester hydrolase has been found in the nuclear and cytosolic fractions of liver homogenates. This enzyme is stimulated by bile salts and has properties nearly identical to those observed for... [Pg.51]

Some sulfatases (sulfuric ester hydrolases, EC 3.1.6) play a pharmacological role in the hydrolysis of sulfuric acid ester metabolites and the few such esters that are used as prodrugs. Arylsulfatase (sulfatase, arylsulfohydrolase,... [Pg.56]

F. J. Leinweber, Possible Physiological Roles of Carboxylic Ester Hydrolases , Drug Metab. Rev. 1987, 18, 379-439. [Pg.62]

S. Wee, W. M. Grogan, Testicular Temperature-Labile Cholesteryl Ester Hydrolase , J. Biol. Chem. 1993, 268, 8158-8163. [Pg.63]

H. K. Bhat, G. A. S. Ansari, Cholesterol Ester Hydrolase Mediated Conjugation of Ha-loethanols with Fatty Acids , Chem. Res. Toxicol. 1990, 3, 311 -317. [Pg.93]

In addition to these various phosphatases, carboxylic ester hydrolases interact with phosphates and/or phosphonates. The carboxylesterases (EC... [Pg.567]

A number of enzymes known as sulfuric ester hydrolases (EC 3.1.6) are able to hydrolyze sulfuric acid esters. They comprise arylsulfatase (sulfatase, EC 3.1.6.1), steryl-sulfatase (steroid sulfatase, steryl-sulfate sulfohydrolase, arylsulfatase C, EC 3.1.6.2), choline-sulfatase (choline-sulfate sulfohydrolase, EC 3.1.6.6), and monomethyl-sulfatase (EC 3.1.6.16). Whereas mono-methyl-sulfatase is highly specific and does not act on higher homologues, arylsulfatase has a broad substrate specificity and is of particular significance in the hydrolysis of sulfate conjugates of phenols, be they endogenous compounds, drugs, or their metabolites [167-169],... [Pg.594]

This is a broad class of enzymes that catalyze the hydrolysis of esters some of these enzymes are quite specific. See also Cholesteryl Ester Hydrolase specific esterase... [Pg.272]

CHOLESTERYL ESTER HYDROLASE OHOLINE AOETYLTRANSFERASE OHOLINE DEHYDROGENASE OHOLINE KINASE OHOLINE OXIDASE Oholine phosphatase,... [Pg.731]

CHOLESTERYL ESTER HYDROLASE ESTER HYDROLYSIS MECHANISMS ETA (7,)... [Pg.741]

Okamura, S. and Watanabe, M., Purification and properties of hydroxycinnamic acid ester hydrolase from Aspergillus japonicus. Agric. Biol. Chem. 46, 1839, 1982. [Pg.312]

Tunicamycin and 2-deoxy-D-arahino-hexose interfere with the expression of lipase (glycerol-ester hydrolase, EC 3.1.1.3) in cultured, mesenchymal rat-heart cells. The causes of inhibition were not inves-... [Pg.377]

A-type carboxylic ester hydrolases (arylesterases EC 3.1.1.2), which hydrolyse aromatic esters, e.g. phenylacetate they show little activity on tributyrin, and are not inhibited by organophosphates. [Pg.241]

Cholesteryl ester degradation Most dietary cholesterol is present in the free (nonesterified) form, with ten to fifteen percent present in the esterified form. Cholesteryl esters are hydrolyzed by pancreatic cholesterol ester hydrolase (cholesterol esterase), which produces cholesterol plus free fatty acids (see Figure 15.2). Cholesteryl esteh hydrolase activity is greatly increased in the presence of bile salts. ... [Pg.173]

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