Developmental change in activity of N-acetyl-beta-glucosaminidase and a comparison of its multiple enzyme activities in the masseter muscle of normal and dystrophic mice.

N-acetyl-ƒÀ-glucosaminidase (NAG, EC 3.2. 1.30) is an enzyme which catalyzes glycoproteins, glycolipids and glycosaminoglycans. This enzyme is widely distributed in a variety of tissues and fluids of mammals. Until now, NAG has been purified from various organs such as human placenta1), bovine spleen2), horse kidney3) and mouse submandibular gland4), and its enzymatic properties have been reported. However, there is little information available on the properties of NAG in skeletal muscle. Recently, we measured activities of several lysosomal enzymes in the masseter muscle, the major muscle of mastication, of adult normal and muscular dystrophic mice, and found a marked increase of NAG activity in the dystrophic muscle5). In this study, we examined the developmental change of NAG activity in the masseter muscle of normal and dystrophic mice. In addition, we compared the activities of multiple forms of NAG in the muscle of both animals.