4-Methylumbelliferyl 2-acetamido-2-deoxy-alpha-D-glucopyranoside, a fluorogenic substrate for N-acetyl-alpha-D-glucosaminidase.

Condensation of dimeric 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-alpha-D-glucopyranosyl chloride with 4-methylumbelliferone gave crystalline 4-methylumbelliferyl 3,4,6-tri-O-acetyl-2-deoxy-2-oximino-alpha-D-arabino-hexopyranoside. Acetylation of this adduct, reduction of the resulting crude O-acetyloxime with borane in oxolane, and acetylation gave the 3,4,6-tri-O-acetyl derivative of 4-methylumbelliferyl 2-acetamido-2-deoxy-alpha-D-glucopyranoside (1). A new sensitive assay of N-acetyl-alpha-D-glucosaminidase (EC 3.2.1.50) is made possible by fluorometric measurement of 4-methylumbelliferone liberated by enzymic hydrolysis of glycoside 1. Such assays are illustrated by results obtained with enzyme preparations from pig liver and human-blood serum.