Mutant Alanine Racemase (Y354N) (mAR-Y354N)，a pyridoxal 5- phosphate (PLP) dependent enzyme catalyzes the interconversion of the L-Serine to D-Serine. In WT Alanine Racemase Tyr354 plays a crucial role in defining the strict specificity of AR for alanine，in converting L-Alanine to D-Alanine，which is an important component of the peptidoglycan layer of bacterial cell wall. By mutating the active site Tyr 354 to Asn，the specificity of the enzyme changes and it becomes a racemase with dual specificity for L- Alanine and L-Serine.
