Peculiar features of four enzymes of the CaLA superfamily in aqueous media: Differences in substrate specificities and abilities to catalyze alcoholysis

With 31% of identity with the Lipase A of Candida antarctica (CaLA), the promising lipase/acyltransferase from Candida parapsilosis (CpLIP2) can be classified in the original CaLA-like superfamily. Contrary to CaLA, CpLIP2 has the exceptional property to catalyze acyltransfer reactions preferentially to hydrolysis even in aqueous media with high thermodynamic activity of water (a(w) > 0.9). Two new enzymes, CtroL4 from Candida tropicalis and AflaL0 from Aspergillus flavus, homologous to the CaLA-like superfamily proteins were obtained by heterologous production and used for comparative functional characterization in aqueous media. The ability of the lipases to catalyze acyltransfer reaction in water was correlated with their degree of homology with CpLIP2, indicating a global sequence/function relationship that could be very useful for the selection of new biocatalysts of high industrial interest. The four enzymes exhibited different substrate specificity profiles, considering the length and the carbon chain unsaturation degree of the acyl group in the donor ester, and the class and the position of the hydroxyl group of the acyl accepting alcohol. Within the lipases sequences, peculiar variability in the (putative) substrate binding site was observed and will be further investigated for the elucidation of structure/function relationships. (c) 2013 Elsevier B.V. All rights reserved.