AmpD

__**AmpD: Anhydro-//N//-Acetylmuramyl-L-Ala Amidase**__

E. coli strains lacking AmpD contain large amounts of anhMurNAc-tripeptide in their cytoplasms.

AmpD in the cytoplasm rapidly cleaves anh-MurNAc-peptides. However, the rate of cleavage of MurNAc-peptides and UDP-MurNAc-pentapeptide is at least 10,000 times slower than that of the anhMurNAc-tripeptide. Hence, AmpD rapidly cleaves anh-MurNAc-peptides, without destroying the UDP-MurNAc-pentapeptide needed for the synthesis of peptidoglycan.

AmpD contains a zinc ion which is essential for it's activity. This can be seen from the fact that replacement of each of the zinc-triad amino acids (His34, His154 and Asp164) which results in the loss of a zinc ion from the active site abolishes it's amidase activity.