Manipulation of the active site loops of D-hydantoinase, a (beta/alpha)8-barrel protein, for modulation of the substrate specificity

A study was done to modulate the substrate specificity of BstHYD for the synthesis of commercially important non-natural amino acids by rationally manipulating the stereochemistry gate loops (SGLs) on the basis of the structural analysis and comparison of the SGLs of the three different hydantoinases (BstHYD, BthHYD, and PhHYD). Findings of the study indicate that the amino acid residues of SGLs forming the substrate-binding pocket are critical for the substrate specificity of D-hydantoinase, and the findings also imply that substrate specificities of cyclic amidohydrolase family enzymes can be modulated by rational design of these SGLs.