ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
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 β-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 α-methyl-d-mannoside against inhibition 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1980.tb06273.x
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