Fructose 1:6 bisphosphatase activity in the liver and testis of rats and goats.

1. The activity of the enzyme Fructose 1:6 Bisphosphatase (FDPase) was studied in the liver and testis of adult goats and rats. No significant difference in the enzyme activity was observed between liver and testis of rats. Highly significant differences (P less than 0.01) were observed between the activity of goat liver and goat testis, goat liver and rat liver, goat testis and rat testis; the activities being higher in goat tissues. 2. Homogenization of the tissues with water, 0.05 M lactate buffer (pH 3.5), 150 mM KCl and 0.34 M sucrose yielded highest activity with water and lactate buffer followed by Sucrose and KCl. 3. 10 microM of Fe2+ and 45 microM of Zn2+ decreased the enzyme activity of rat testis by 39% and 93% respectively. 4. The rate of hydrolysis of FDP with respect to time in rat liver and testis was a first order reaction. Linear kinetics of the substrate hydrolysis was observed up to 90 min. No substrate inhibition of the enzyme activity was observed up to 50 microM of the substrate. Km of rat liver and testis FDPase were 8.3 microM and 10.5 microM respectively.