The reactive serine residue in phosphoglucomutase of Micrococcus lysodeikiticus.

1. Phosphoglucomutase of Micrococcus lysodeikticus was labelled at the active site by exchange with (32)P-labelled substrates of high specific radioactivity. 2. Partial acid hydrolysis gave rise to radioactive peptides; serine phosphate was identified as one of the derivatives. 3. Comparison of the other (32)P-labelled peptides with the peptides obtained from the (32)P-labelled rabbit muscle phosphoglucomutase indicates that the sequence around the reactive serine residue is identical in both enzymes.