Kinetics of cross-linking of peptidoglycan in Bacillus megaterium.

The extent and rate of cross-linking of diaminopimelic acid in the peptidoglycan of Bacillus megaterium have been determined by a new procedure. The method is based on the reaction of nitrous acid with the unprotected amino groups of non-cross-linked diaminopimelic acid. Pulse label experiments in a mutant where diaminopimelic acid is incorporated specifically into peptidoglycan demonstrated that the cross-linking reaction continued for many minutes after incorporation of precursor subunits into peptidoglycan. The method has been used to demonstrate the sensitivity of the cross-linking reaction to penicillin in viva. Models for assembly of peptidoglycan are discussed.