Determination of amino acids and dipeptides is correlated significantly with optimum temperatures of microbial lipases

Amino acids and dipeptides that are correlated significantly with lipase optimum temperatures were searched for in 34 microbial lipase sequences by a stepwise regression method. The positive dipeptides were found to be IR, KS, NY, SA, ST and YR, whereas negative ones were DK, DY, IS, KA, WS, YS and QI. The calculated optimum temperatures from an optimal regression equation of dipeptides fitted the corresponding experimental optimum temperatures of lipases very well, and the maximal absolute difference was only 3.43°C. The spatial positions of the related dipeptides were searched for in two known crystal structures of a thermophilic and mesophilic lipase, respectively. Most of the positive dipeptides were sited in the α-helices, while the negative ones were located mainly in the β-strands or coils and about half of them existed in the N- or C-terminii of the lipases. The results obtained will be very useful in lipase engineering for enhancing lipase thermostability.