Poly(aspartic acid) is a biodegradable water-soluble polymer. It has been studied as an alternative to traditional anionic water-soluble polymers such as poly(acrylic acid). It also has potential uses in scaffolding for tissue growth, artificial skin, drug delivery and other biomedical applications. In our group, oligo(b-ethyl-aspartate) was synthesized by a green, efficient and cost-effective protease catalysis approach. Various proteases were evaluated as catalysts and a-chymotrypsin was found to be most efficient. Papain, which was highly active for the oligomerization of L-glutamic acid diethyl ester oligomerization was inactive for L-aspartic acid diethyl ester oligomerization. The efficiency of a-chymotrypsin for the synthesis of oligo(b-ethyl-aspartate) was studied under various conditions (pH, temperature, buffer concentration, solvent concentration, co-solvent and reactant/catalyst concentrations). The preferred reaction conditions were pH 8.5, 40 <sup>o</sup>C, and 5 min reaction time. Chain lengths distribution of the oligopeptide obtained was 8-25. To fully understand protease specificity for this reaction, computational modeling was performed using the Rosetta software. Simulations were run to determine the relative energies of substrate docking to papain and a-chymotrypsin active sites in which the respective enzyme-acyl complexes of aspartate and glutamate had been formed. These calculations provided insights into molecular determinants of the substrate selectivity for peptide bond formation for the two proteases.

Investigation of protease-catalyzed L-aspartic acid diethyl ester oligomerization and active site computational modeling

254th National Meeting (2017)

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