Hepatic lipase acylates dolichol in the presence of a plasma cofactor in vitro.
Phosphatidylethanolamine:dolichol acyltransferase (PEDAT), an enzyme previously partially purified and characterized in rat liver [Sindelar, P., Chojnacki, T., & Valtersson, C. (1992) J. Biol. Chem. 267, 20594-20599], is here purified to homogeneity from a heparin perfusate of rat liver and is shown to be identical to hepatic lipase. However, in contrast to triglyceride hydrolysis by hepatic lipase, the PEDAT activity is strongly dependent on a heat-stable plasma cofactor. This cofactor stimulates the activity up to 15-fold and shifts the pH optimum for the reaction from 8.5 to 7.5. Upon gel filtration on Bio-Gel A-1.5, the factor is heterogeneously distributed, with a major peak at 220 kDa. The dolichol-acylating activity can also be detected in rat adrenals and ovaries, and evidence is presented that the PEDAT assay shows a higher degree of specificity for hepatic lipase than the standard assay with triolein-gum arabic emulsion in 1 M NaCl.
Sindelar
P
P
Clinical Research Centre at Huddinge Hospital, Karolinska Institutet, Stockholm, Sweden.
Valtersson
C
C
D000215:Acylation; D000217:Acyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D000311:Adrenal Glands / Q000201:enzymology; D000818:Animals; D003067:Coenzymes / Q000097:blood; D004286:Dolichols / Q000378:metabolism*; D005260:Female; D006801:Humans; D008049:Lipase / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D010053:Ovary / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley
D003067:Coenzymes; D004286:Dolichols; D000217:Acyltransferases; C077400:phosphatidylethanolamine - dolichol acyltransferase; D008049:Lipase