Distinction between esterases and lipases: comparative biochemical properties of sequence-related carboxylesterases.
Carboxylesterases (Carboxyl ester hydrolase) include two groups of enzymes, namely non-specific esterases (EC 3.1.1.1) and lipases (EC 3.1.1.3) which have been early differentiated on the basis of their substrate specificity. Esterases hydrolyse solutions of water-soluble short acyl chain esters and are inactive against water-insoluble long chain triacylglycerols which, in turn, are specifically hydrolyzed by lipases. Based on the comparison of the primary structures, three families of sequence-related carboxylesterases, namely the lipoprotein lipase family (L-family), the hormonesensitive lipase family (H-family) and the cholinesterase family (C-family) have been identified. Using solutions and emulsions of vinyl, glyceryl and p-nitrophenyl esters, we have reinvestigated the kinetic properties of some esterases and lipases of the H- and C-families. Results indicate that esterases and lipases, which are both active on soluble esters, can be differentiated by their value of Km. Moreover, esterase, unlike lipases, are inactive against water-insoluble esters as vinyl laurate and trioctanoylglycerol. From the the comparison of structural features of sequence-related esterases and lipases, it appears that lipases, unlike esterases, display a significant difference in the distribution of hydrophobic amino acid residues at vicinity of their active site. This observation supports the hypothesis of the existence in lipases of a particular surface domain that specifically interacts with lipid-water interfaces and contributes to the transfer a single substrate molecule from the organized lipid-water interface (supersubstrate) to the catalytic site of the enzyme.
Chahinian
H
H
Laboratoire de Biochimie et Physico-chimie des Membranes, Faculté St-Jérôme, Université Paul Cézanne, Marseille, France.
Sarda
L
L
D000596:Amino Acids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004950:Esterases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008049:Lipase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D000596:Amino Acids; D004950:Esterases; D002265:Carboxylic Ester Hydrolases; D008049:Lipase