Biochemical compartmentation of fish tissues. Hexokinase in the brain.

Differential distribution of gross, particulate and soluble forms of hexokinase in the cerebrum, cerebellum, pituitary, hypothalamus and thalamus and medulla oblongata was studied in 9 inland teleosts of different phylogenetic age to clarify the compartmentation of glucose metabolism. Enzyme activity (gross) was maximum in the cerebrum and minimum in the medulla oblongata, suggesting that glucose metabolism is more intensive in the former structure. The activity in the particulate fraction was highest in the cerebellum followed by the cerebrum, midbrain and medulla oblongata. Gross, particulate and soluble fraction of the enzyme was higher in major carp species than in cat fish or snake head species. Total particular and soluble fraction was highest in the cerebrum, cerebellum and midbrain. The distributional trend of the enzyme was similar in the 9 fishes.