Abstract: Transglutaminase (EC22.214.171.124, TGase) is an important food enzyme. In order to enhance its catalytic activity, the amino acid sites that could affect the binding energy of S. mobaraense TGase and its substrate α-N-CBZ-GLN-GLY were predicted through Discovery Studio 2017. Then mutants (Y24W, E300W and Y302R) with reduced binding energy were constructed. Compared with wild type of TGase, the specific activity of E300W was increased by 31%. Km, kcat and kcat/Km vaule of E300W were increased by 10%, 42% and 29% respectively. The results showed that the increase of specific enzyme activity was mainly due to the increase of enzymatic conversion number. While the thermal stability of all the mutants decreased in varying degrees. And the structure analysis indicated that the main-chain hydrogen bonds of Y24W, E300W and Y302R decreased by 1, 2 and 4, respectively, compared with original TGase. These results suggested that the strategy based on the analysis of binding free energy could rapidly identify the key amino acids that affect the catalytic activity of TGase, and further mutation might effectively improve its catalytic activity.
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