Transketolase activities and body weight changes in rats on low protein diets

Transketolase activity was studied in rats fed a peasant diet containing 5.9% protein, carbohydrate diets (sucrose, glucose, lactose and starch, each containing 5.0% protein) and a normal diet which contained 21% protein. The activity of the enzyme in red cell hemolysate was independent of the protein content of these diets. However, rats fed a low protein diet had significantly higher hepatic transketolase activity than those fed the normal diet. The hepatic transketolase activity was highest in rats fed a diet containing 4 mg thiamine/kg diet. Further dietary increase in the levels of this vitamin did not cause any further increase in the level of activity of the enzyme, thus suggesting that excess dietary thiamine may have a minimal effect on the activity of this enzyme.