Origin of glycine from acid hydrolysis of the -lactam antibiotic A16886B

Structural analysis of two new beta-lactam antibiotics, A16884A and A16886B, indicated that they, like cephalosporin C, were composed of modified valine and cysteine residues, and alpha-aminoadipic acid. However, acid hydrolysis of A16886B and A16884A produced three times as much glycine as did hydrolysis of cephalosporin C under the same conditions. Samples of A16886B-(14)C-6 and A16886B-(14)C-8 were prepared by the addition of cysteine-(14)C-3 and cystine-(14)C-1 to fermentations of Streptomyces clavuligerus. The specific activity of glycine obtained from hydrolysis of A16886B-(14)C-6 was considerably higher than that from hydrolysis of A16886B-(14)C-8. An explanation for the difference in amounts of glycine obtained from hydrolysis of these antibiotics is discussed.