Isolation of a low-molecular-weight antibacterial system from human amniotic fluid

A low-molecular-weight antibacterial system has been isolated from human amniotic fluid. The bacterial inhibitor requires the metal cation zinc and a peptide with a molecular weight of 630. The peptide component was purified using ultrafiltration, gel filtration, and ion-exchange chromatography. It can be inactivated by digestion with carboxypeptidase. The amino acid composition of the peptide is: 3 glutamine-glutamic acid, 2 glycine, and 1 lysine. Removal of zinc from the peptide has been shown to remove bacterial inhibitory activity.