Identification of Amino Acid Residues Relevant to Substrate Specificity and Enantioselectivity

2 Identification of Amino Acid Residues Relevant to Substrate Specificity and Enantioselectivity 

With respect to the carboligase activity, PDCI472A proved to be a real chimera between PDC and BFD, while BVDA460I/F464I provided the most interesting result with an almost complete reversal of the stereochemistry of its 2-hydroxy-propiophenone product [7, 9]. 

3 Optimization of the Substrate Range of BFD by Site-Directed Mutagenesis 

Since wild-type BFD does not accept ortho-substituted benzaldehydes as donor substrates, the variant BFDH281A with an enlarged active site was prepared by site-directed mutagenesis of histidine-281 to alanine. This variant shows an activity higher by a factor of 140 with respect to the formation of (R)-benzoin. Furthermore, BFDH281A allows the selective formation of mixed substituted (P)-benzoins by employment of appropriate substrate combinations [10]. 

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