Esterases receive special attention because their wide distribution in biological systems and environments and their importance for physiology and chemical synthesis. The prediction of esterases substrate promiscuity level from sequence data and the molecular reasons why certain such enzymes are more promiscuous than others, remain to be elucidated. This limits the surveillance of the sequence space for esterases potentially leading to new versatile biocatalysts and new insights into their role in cellular function. Here we performed an extensive analysis of the substrate spectra of 145 phylogenetically and environmentally diverse microbial esterases, when tested with 96 diverse esters. We determined the primary factors shaping their substrate range by analyzing substrate range patterns in combination with structural analysis and protein-ligand simulations. We found a structural parameter that helps ranking (classifying) promiscuity level of esterases from sequence data at 94% accuracy. This parameter, the active site effective volume, exemplifies the topology of the catalytic environment by measuring the active site cavity volume corrected by the relative solvent accessible surface area (SASA) of the catalytic triad. Sequences encoding esterases with active site effective volumes (cavity volume/SASA) above a threshold show greater substrate spectra, which can be further extended in combination with phylogenetic data. This measure provides also a valuable tool for interrogating substrates capable of being converted. This measure, found to be transferred to phosphatases of the haloalkanoic acid dehalogenase superfamily and possibly other enzymatic systems, represents a powerful tool for low-cost bioprospecting for esterases with broad substrate ranges, in large scale sequence datasets.
Title: Optimization of lipase-catalyzed synthesis of sorbitan acrylate using response surface methodology Jeong GT, Park DH Ref: Appl Biochem Biotechnol, 137-140:595, 2007 : PubMed
In this study, we have synthesized sorbitan acrylate through response surface methodology, using sorbitan and vinyl acrylate that catalyze immobilized lipase. In order to optimize the enzymatic synthesis of the sorbitan acrylate, we applied response surface techniques to determine the effects of five-level-four-factors and their reciprocal interactions with the biosynthesis of sorbitan acrylate. Our statistical model predicted that the highest conversion yield of sorbitan acrylate would be approx 100%, under the following optimized reaction conditions: a reaction temperature of 40.1 degrees C, a reaction time of 237.4 min, an enzyme concentration of 8%, and a 4.49:1 acyl donor/acceptor molar ratio. Using these optimal conditions in three independent replicates, the conversion yield reached 97.6+/-1.3%.
