Reversal by a specific peptide (diacetyl-alpha gamma-L-diaminobutyryl-D-alanyl-D-alanine) of vancomycin inhibition in intact bacteria and cell-free preparations.

Vancomycin inhibited the growth of Bacillus megaterium, Staphylococcus aureus and Micrococcus lysodeikticus, and in cell-free preparations from B. megaterium it inhibited the formation of mucopeptide and enhanced the accumulation of the lipid intermediate in the biosynthetic pathway. All these inhibitory processes were reversed by the presence of a synthetic peptide analogous to un-cross-linked mucopeptide side chains, namely diacetyl-l-diaminobutyryl-d-alanyl-d-alanine. A considerable amount of vancomycin was found in recovering cells, whether recovery was caused by peptide or took place naturally because a low initial concentration of antibiotic was used. In cell-free preparations pretreated with vancomycin, continued inhibition of mucopeptide synthesis depended on the presence of cell-wall material. This inhibition was also reversible by added peptide.