title: Further studies on the physico-chemical properties of Rhizopus nodosus acid lipase.
abstract: The Km value of R. nodosus acid lipase was found to be 5 X 10(-2) M and 8 X 10(-3) M with olive oil and tricaprylin respectively. The lipase hydrolyzed triglycerides better than synthetic detergents and methyl esters. When synthetic triglycerides varying in fatty acid chain length were used, maximum hydrolysis was observed with tricaprylin as the substrate. Positional specificity studies indicated a preference for primary esters. The lipase was activated by albumin, NaCl and taurocholate whereas heparin had no effect. The lipase contains a single polypeptide chain with 298 amino acid residues. Glutamic acid and isoleucine were found to be the amino and carboxy-terminal residues, respectively. By gel filtration and SDS-PAGE the molecular weight was determined to be 40,000 +/- 500. The lipase was susceptible to photooxidation in the presence of methylene blue and Rose bengal whereas PMSF and thiol-group specific reagents had no appreciable effect on the lipase activity. NBS inactivated the lipase. Tryptophan residues were found to be essential for the lipase activity.
mesh_terms: D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D046911:Macromolecular Substances; D008751:Methylene Blue / Q000378:metabolism; D008970:Molecular Weight; D010782:Photolysis; D012233:Rhizopus / Q000201:enzymology*; D012395:Rose Bengal / Q000378:metabolism; D013379:Substrate Specificity; D014280:Triglycerides
chemical_list: D046911:Macromolecular Substances; D014280:Triglycerides; D012395:Rose Bengal; D008049:Lipase; D008751:Methylene Blue