[Distribution of 5'-nucleotidase activity in the subcellular fractions of rabbit brain cortex].

The specific activity of 5'-nucleotidase was measured in the fractions of myelin, synaptic membranes, heavy and light synaptosomes and purified mitochondria of brain cortex of intact rabbits. The enzyme specific activity in these fractions was practically the same and made up to 2.2, 2.1, 1.98 and 1.8 mkmoles of Pn per mg of protein per hr. The differences between the specific activities of the four fractions were statistically insignificant. The 5'-nucleotidase activity of the heavy synaptosome fraction was 2 times as low as that of the other fractions as was equal to 0.92 mkmoles of Pn per mg of protein per hr. This value is statistically different from those obtained during the analysis of the other fractions.