A combined assay of three lysosomal marker enzymes: acid phosphatase, beta-D-glucuronidase, and beta-N-acetyl-D-hexosaminidase.

A simplified and rapid method for simultaneous activity measurements of three lysosomal marker enzymes, acid phosphatase, beta-glucuronidase, and beta-N-acetyl-D-hexosaminidase is described. The incubation is carried out in a single test tube and stopped by adding an alkaline sodium dodecyl sulfate solution, thus avoiding centrifugations and allowing for higher Triton X-100 concentrations in the incubation media. Two products of the beta-glycosidases (phenolphthalein and 2-nitrophenolate) are measured spectrophotometrically at the respective wavelengths (555 and 420 nm), and one of the acid phosphatase products is quantitatively determined by measuring inorganic phosphate.