Isolation of cephalosporin C, a penicillin-like antibiotic containing d -α-aminoadipic acid

EXPERIMENTS ON BACITRACIN A 651linked to the e-amino group.However, certain properties of a substance containing lysine and aspartic acid raise the question whether its structure is more complicated than that of a simple dipeptide.5.One of the aspartic acid residues in bacitracin A is readily liberated by hydrolysis in the free state.The second residue is linked to lysine by a bond which is unusually resistant to hydrolysis.A fraction which contained mainly the first aspartic acid was separated from a fraction which contained mainly the second.In one experiment the two fractions were subjected separately to the action of D-aspartic acid oxidase.In another the aspartic acid in each fraction was isolated and its specific rotation measured.The results indicate that the easily liberated aspartic acid is derived from a residue with the D-configuration and that the aspartic acid residue next to lysine has the L- configuration.We wish to thank Dr F. Sanger, F.R.S., for a sample of a-DNP-lysine, and the Commercial Solvents Corporation, Terre Haute, Indiana, U.S.A., for generous gifts of baci- tracin.We are grateful to Mis8 M. Read and Mrs A.Talboys for expert