Aron, H. (University of California, Santa Barbara), H. H. Yonenaka, and H. I. Nakada. Glucosamine-6-phosphate degradation by Proteus vulgaris and isolation of phosphoglucosaminisomerase. J. Bacteriol. 87:1123–1128. 1964.—The presence of the enzyme, phosphoglucosaminisomerase, was demonstrated in a strain of Proteus vulgaris. Fructose-6-phosphate and ammonia were shown to be the primary reaction products. The optimal pH was 7.2 with a broad peak. This differs from previously reported bacterial phosphoglucosaminisomerases which had a pH optimum of about 5.8. Other properties of the enzyme are presented.