HYDROLYTIC SELECTIVITY OF PATATIN (LIPID ACYL HYDROLASE) FROM POTATO (SOLANUM TUBEROSUM L.) TUBERS TOWARD VARIOUS LIPIDS

Abstract

The fatty acid and positional hydrolytic selectivity of lipid acyl hydrolase (LAH; patatin) isolated from potato tubers was determined for acylgfycerol and phospholipid substrates. LAH was about 3-fold more selective for decanoyl residues over other acyl groups of 8–18 carbons for partial glyceride substrates. For both mono- and diacylglycerols, LAH preferred substrates with primary (sn-1 (3)-) ester linkages, indicating a regiobias for these sites over sn-2-linked acyl groups. Similarly, hydrolytic activity on phospholipid substrates was 5- to 10-fold faster on sn-l-palmitoyl, sn-2-lysophospholipids than on intact phospholipids, indicating a preference for either lysophospholipids or sn-l-acyl sites, or both. LAH activity on partial glycerides was not activated by CaCl2 and had a greater temperature optimum relative to LAH activity on phospholipid substrates. These differences are likely based on differences in forces and structural features conferring enzyme-substrate recognition for these substrates within a common active site.