The metabolic fate of 14C-labeled peptidoglycan monomer in mice. I. Identification of the monomer and the corresponding pentapeptide in urine.

The distribution of radioactive products in mouse urine following intravenous administration of the 14C-labeled peptidoglycan monomer, GlcNAc-MurNaC-L-Ala-D-isoglutamine-meso-diaminopimelic acid-D-Ala-D-Ala, has been studied. 60--80% of radioactivity was recovered within first 3 h, 4--8% in the next 3 h and 2--7% in the following 18 h. The majority of the label was associated with the unchanged peptidoglycan monomer (42--56% of the dose). 14--21% of the label was incorporated into a compound which was isolated and tentatively identified as L-Ala-D-isoglutamine-meso-diaminopimelic acid-D-Ala-D-Ala. The kinetics of excretion and the distribution of radioactivity did not differ in immunized, when compared to non-immunized, mice.