Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzymes, Proteobacterial Alanine Racemases
This subfamily is composed mainly of proteobacterial alanine racemases (EC 18.104.22.168), fold type III PLP-dependent enzymes that catalyze the interconversion between L- and D-alanine, which is an essential component of the peptidoglycan layer of bacterial cell walls. hese proteins are similar to other bacterial ARs and are fold type III PLP-dependent enzymes containing contains an N-terminal PLP-binding TIM-barrel domain and a C-terminal beta-sandwich domain. They exist as homodimers with active sites that lie at the interface between the TIM barrel domain of one subunit and the beta-sandwich domain of the other subunit. Homodimer formation and the presence of the PLP cofactor are required for catalytic activity.