5'-nucleotidase in rat brain myelin.
Rat brain myelin showed substantial activity of 5'-nucleotidase. The specific activity in myelin was enriched two- to threefold over that in rat brain homogenates, and the total activity in myelin accounted for approximately 24% of the activity in the homogenates. The 5'-nucleotidase in the homogenates and in isolated myelin had optimum activity at pH 7.5--9.0, was stimulated by Mg2+ and Mn2+, and was inhibited by Co2+, Zn2+, EDTA, and EGTA. 5'-AMP, 5'-UMP, and 5'-CMP were the preferred substrates, and 5'-GMP was hydrolyzed at approximately one-half the rate of the other mononucleotides. The very low rates of cleavage of beta-glycerophosphate and 2'-AMP ruled out any significant contribution of nonspecific phosphatase to the observed 5'-nucleotidase activity in myelin. The 5'-nucleotidase was inhibited by concanavalin A and was protected by alpha-methyl-D-mannoside against inhibited by that lectin, suggesting that this enzyme in the CNS is a glycoprotein. It is concluded from these data, and from histochemical observations made in other laboratories, that the myelin sheath is one major locus of 5'-nucleotidase in the rat brain.
D015720:5'-Nucleotidase; D000818:Animals; D001921:Brain / Q000201:enzymology*; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008766:Methylmannosides / Q000494:pharmacology; D009186:Myelin Sheath / Q000187:drug effects / Q000201:enzymology*; D009708:Nucleotidases / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D008766:Methylmannosides; D003208:Concanavalin A; D008345:Manganese; D009708:Nucleotidases; D015720:5'-Nucleotidase; D008274:Magnesium