Assay of Urinary N-Acetyl-f3-glucosaminidasein a CentrifugalAnalyzer

We describe a kinetic, fluorometric assay for urinary Nacetyl-j3-glucosaminidase (EC 3.2.1.30) by measurement of the release of 4-methylumbelliferone (7-hydroxy-4-methylcoumarin). The method is simple, involving only a single reagent, and is applicable to the assay of other enzymes that hydrolyze similar fluorescent-labeled substrates. The enzyme distribution in human tissues and fluids is described. The enzyme is present in high concentrations in human kidney, liver, and lung. Its concentration in urine is shown to be a sensitive indicator of early renal damage, which precedes changes in serum creatinine and urinary protein. Assay of the enzyme is quite useful in monitoringrenal damage due to myoglobinuria.