Document Detail

Specificity of purified monoacylglycerol lipase, palmitoyl-CoA hydrolase, palmitoyl-carnitine hydrolase, and nonspecific carboxylesterase from rat liver microsomes.
MedLine Citation:
PMID:  6141766     Owner:  NLM     Status:  MEDLINE    
The comparative substrate specificities of five purified serine hydrolases from rat liver microsomes have been investigated, especially their action upon natural lipoids. All enzymes had high carboxylesterase activities with simple aliphatic and aromatic esters and thioesters. The broad pH optima were in the range of pH 6-10. Synthetic amides were less potent substrates. The hydrolytic activities towards palmitoyl-CoA and monoacyl glycerols were generally high, whereas phospholipids and palmitoyl carnitine were cleaved at moderate rates. Acetyl-CoA, acetyl carnitine, and ceramides were not cleaved at all. The closely related hydrolases with the highest isoelectric points (pI 6.2 and 6.4) were most active with palmitoyl-CoA and palmitoyl glycerol. One of these enzymes might also be responsible for the low cholesterol oleate-hydrolyzing capacity of rat liver microsomes. Among the other hydrolases, that with pI 6.0 showed significant activities with simple butyric acid esters, 1-octanoyl glycerol, and octanoylamide. The esterase with pI 5.6 had the relatively highest activities with palmitoyl carnitine and lysophospholipids. The purified enzyme with pI 5.2 showed some features of the esterase pI 5.6, but generally had lower specific activities, except with 4-nitrophenyl acetate. The lipoid substrates competitively inhibited the arylesterase activity of the enzymes. The varying activities of the individual hydrolases were influenced in parallel by a variety of inhibitors, indicating that the purified hydrolases possessed a relatively broad specificity and were not mixtures of more specific enzymes. The nomenclature of the purified hydrolases is discussed.
R Mentlein; M Suttorp; E Heymann
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of biochemistry and biophysics     Volume:  228     ISSN:  0003-9861     ISO Abbreviation:  Arch. Biochem. Biophys.     Publication Date:  1984 Jan 
Date Detail:
Created Date:  1984-03-14     Completed Date:  1984-03-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372430     Medline TA:  Arch Biochem Biophys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  230-46     Citation Subset:  IM    
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MeSH Terms
Carboxylic Ester Hydrolases / metabolism*
Glycerides / metabolism
Isoelectric Point
Lipid Metabolism
Microsomes, Liver / enzymology*
Monoacylglycerol Lipases / metabolism*
Palmitoyl Coenzyme A / metabolism
Palmitoyl-CoA Hydrolase / metabolism*
Phospholipids / metabolism
Substrate Specificity
Thiolester Hydrolases / metabolism*
Reg. No./Substance:
0/Glycerides; 0/Phospholipids; 1763-10-6/Palmitoyl Coenzyme A; EC 3.1.1.-/Carboxylic Ester Hydrolases; EC 3.1.1.-/palmitoyl-L-carnitine hydrolase; EC Lipases; EC 3.1.2.-/Thiolester Hydrolases; EC Hydrolase

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