Covalent Linkage of Polyamines to Peptidoglycan in Anaerovibrio lipolytica

Spermidine and cadaverine were found to be constituents of the cell wall peptidoglycan of Anaerovibrio lipolytica, a strictly anaerobic bacterium. The peptidoglycan was degraded with the N-acetylmuramyl-l-alanine amidase and endopeptidase into two peptide fragments, peptide I and peptide II, at a molar ratio of 4:1. Peptides I and II were identified as l-alanine–d-glutamic acid(αcadaverine)γmeso-diaminopimelic acid (DAP)–d-alanine and l-alanine–d-glutamic acid(αspermidine)γmeso-DAP–d-alanine, respectively. The N(1)-amino group of spermidine was linked to the α-carboxyl group of the d-glutamic acid residue of peptide II.