ENDOGENOUS ADP-RIBOSYLATION OF PROTEINS IN MYCOBACTERIUM-SMEGMATIS

Endogenous ADP-ribosylation of two proteins with molecular weights of 30,000 (30K) and 80,000 (80K) was detected in cell extracts of Mycobac terium smegmntis. Modification of these proteins was enzymatic. The AD P-ribose bound to 30K was removed by HgCl2 but not by NH2OH, suggestin g the modification of a cysteine residue. The ADP-ribose bound to 80K was not removed by either HgCl2 or NH2OH, which is consistent with the modification of an asparagine residue. ADP-ribosylation of 80K appear ed to be reversible.