Subcellular Localization of 5′‐Nucleotidase in Rat Brain

Abstract

The subcellular distribution of the ectoenzyme, 5'-nucleotidase, in cerebral cortex and cerebellum of the rat was studied both biochemically and cytochemically. The fractions were characterized biochemically by marker enzymes. The localization of 5'-nucleotidase activity was also investigated cytochemically in the myelin, synaptosomal, mitochondrial, and microsomal fractions. Biochemically 5'-nucleotidase was found to be enriched in the membrane-containing fractions, i.e., myelin, synaptosomal, and microsomal fractions. Cytochemistry showed the reaction product in the myelin fraction to be associated with myelin profiles. In the synaptosomal fraction reaction product could occasionally be seen at synaptosomal membranes, although it could not be attributed unequivocally to the synaptosome itself, since in positions with reaction product unidentifiable membrane structures could always be seen attached. Mitochondria were virtually without any reaction product. In the microsomal fraction 5'-nucleotidase activity was associated with unidentifiable membrane structures. It is concluded that 5'-nucleotidase is associated with myelin profiles and that the high activity found in the synaptosomal fraction is probably not associated with nerve ending plasma membranes.

ATP, ADP and AMP dephosphorylation in membrane fractions of Rhamdia quelen exposed to different temperatures

“…Na + K + ATPase increased 3-12 fold in the brain, hepatic, and renal membrane fraction when compared with the homogenate, and 5¢-nucleotidase (Heymann et al 1984) increased 2-5 fold, confirming that the preparations were enriched with plasma membrane fractions (data not shown).…”

“…All steps were carried out at 4°C. 5¢-Nucleotidase activity was determined as described by Heymann et al (1984). The reaction medium contained 10 mM MgCl 2 and 100 mM Tris-HCl buffer, pH 7.5.…”

Apyrase and 5′-nucleotidase Activities in Synaptosomes from the Cerebral Cortex of Rats Experimentally Demyelinated with Ethidium Bromide and Treated with Interferon-β

“…The reaction was initiated by the addition of ATP or ADP to obtain a final concentration of 1.0 mM and incubation proceed for 20 min in either case. 5¢-Nucleotidase activity was determined essentially by the method of Heymann et al [34] in a reaction medium containing 10 mM MgSO 4 and 100 mM Tris-HCl buffer, pH 7.5, in a final volume of 200 ll. Twenty microliters of enzyme preparation (8-12 lg of protein) were added to the reaction mixture and pre-incubated at 37°C for 10 min.…”

The essential oil from Lippia alba induces biochemical stress in the silver catfish (Rhamdia quelen) after transportation

“…3.1.3.5). Activity was determined by the method of Heymann et al (1984) in a reaction medium containing 10 mM MgSO 4 and 100 mM Tris-HCl buffer (pH 7.5) in a final volume of 200 μL. The tubes were then chilled on ice for 10 min, and the released inorganic phosphates (Pi) were assayed by the method of Chan et al (1986).…”