Biochemical Studies on 5'-Nucleotidase of Schwann Cells in Degenerated Nerve

This report describes the partial characterization of 5'-nucleotidase (5'-AMPase) in Schwann-cell plasmalemmae (PM) prepared from degenerated cat sciatic nerve. 5'-AMPase was enriched 3.7-fold in the PM fraction over that of the crude homogenate preparation. The plant lectin concanavalin-A (Con-A) reduced Schwann cell PM 5'-AMPase activity in a concentration-dependent manner (30-600 micrograms/ml). Plasma membrane 5'-AMPase activity was maximally inhibited to 20% of control values by Con-A (400-600 micrograms/ml), and activity returned to control levels by pretreatment with the hapten sugar alpha-methyl-D-mannoside (50 mM). Equimolar concentrations of UDP and ADP (100 microM) reduced the rate of hydrolysis of labeled AMP to labeled adenosine in PM to 45% and 35% of control, respectively. This is the first study to characterize a Schwann-cell PM enzyme and demonstrates that 5'-AMPase may be used as a Schwann-cell PM marker enzyme.