Cloning, characterization and mutagenesis of Russell's viper venom l-amino acid oxidase: Insights into its catalytic mechanism

► Snake venom LAAOs are divided according to residue 223 substitutions in the phylogeny tree. ► Effects of site-directed mutagenesis at His223 of a viperid LAAOs were examined. ► Residue 223 is important for binding substrate instead of serving as an essential base in the LAAO catalysis. ► The suggested mechanism for SV-LAAOs is a direct hydride transfer from substrate to FAD.