RESUMO
An enzyme with properties similar to rat liver glucokinase (Hexokinase IV or D) is present in salmon liver in addition to low-Km hexokinase(s). The specific activity of this enzyme increases about 1.6 fold, comparing activities after feeding diets with 25% and 0% digestive energy from starch. The enzyme has a low affinity for glucose, S0.5 = 25.2-26.8 mM (95% confidence interval) and a low activity with fructose, approximately 8% of the activity with glucose. Its molecular mass was estimated to 50.7 +/- 0.6 kDa (SEM. n = 3) by gel filtration, and it displays positive cooperativity with respect to glucose. The Hill constant = 1.73-1.81 (95% confidence interval). The enzyme is competitively inhibited by N-acetyl glucosamine, K(i) approximately 0.28 mM.
