Comparison of lipases from different strains of the fungus Geotrichum candidum.

The type A lipase and the cis-9 18:1 specific type B lipase of different strains of Geotrichum candidum were compared. Comparing the enzyme activity of crude lipase preparation and purified type A and type B lipases and the protein pattern of these preparations in denaturing polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the specific activity for cis-9 18:1 fatty acids was related to the content of the type B lipase. Tandem-crossed immunoelectrophoresis was used to demonstrate immunological identity between type A and type B lipase of G. candidum ATCC 66592. Partial immunological identity was observed between type B lipase of this strain and type A lipase of G. candidum ATCC 34614 and two commercial crude G. candidum lipase preparations (Amano and Biocatalyst), i.e., the type B lipase of G. candidum ATCC 66592 had immunogenic epitopes which are not present on the other lipases. Enzymatic deglycosylation of the lipases did not alter this pattern. After partial proteolysis of purified type A and type B lipases of G. candidum ATCC 66592, Amano and Biocatalyst, no difference between the type A lipase of the three strains was observed in SDS-PAGE. For all strains the type B lipase exhibited a distinctly different peptide pattern to that of the type A lipase. In addition, the type B lipase of G. candidum ATCC 66592 differed from the type B lipase of Amano and Biocatalyst by having an additional peptide band. The results indicate that the G. candidum ATCC 66592 should be considered a distinct strain regarding the protein chemical characteristics of its type B lipase, whereas the two commercial lipase preparations appear to be very similar.