2.1.1.235 H123A mutant protein retains catalytic activity, the kcat/Km is reduced to 1.8% compared to the wild-type enzyme 714271 2.1.1.235 H123N mutant protein retains catalytic activity, the kcat/Km is reduced to 0.37% compared to the wild-type enzyme 714271 2.1.1.235 S120A site-directed mutagenesis, the mutant exhibits a modest decrease in its catalytic efficiency compared to wild-type 756061 2.1.1.235 Y14F site-directed mutagenesis, the mutation results in an approximately 30fold decrease in catalytic efficiency compared to wild-type 756061