Purification and characterization of an extracellular lipase from the fungus<i>Rhizopus delemar</i>

Abstract

Abstract The complete purification and characterization of an extracellular lipase (acylglycerol acylhydrolase, EC 3.1.1.3) from R. delemar is described. The final product was homogeneous as judged by electrophoresis in denaturing polyacrylamide gels and by isoelectric focusing, and was shown by means of an activity stain to be lipolytic. The purified enzyme had a monomer molecular weight of 30,300, an isoelectric point of 8.6, and approximately one monosaccharide moiety per molecule. N ‐Terminal sequence data (28 residues) and the amino acid composition of the lipase indicated that it corresponds to the product of a lipase‐encoding cDNA previously isolated from R. delemar . Optimal activity occurred between pH 8.0 and 8.5. The activity and stability of the enzyme were maximum at 30°C. Divalent cations were required for activity, with barium, calcium and manganese conferring maximum activity. Activation by calcium was maximal at and above 10 mM. The lipase was not inactivated by reducing agents, sodium fluoride or phenylmethlsufonyl fluoride. It was resistant to N ‐ethylmaleimide, and inactivated by p ‐chloromercuribenzoic acid in a manner which was not reversed by cysteine.