Participation of propionate in cholesterol biosynthesis by rat liver

Incorporation of (214C) propionate into cholesterol was demonstrated using rat liver slices and homogenates. The incorporation of (214C) propionate was greater than that of (214C) acetate. Using the same liver homogenate preparation (214C) succinate and (214C) pyruvate were incorporated into cholesterol to a lesser extent than (214C) acetate and (214C) propionate. Addition of unlabeled acetate failed to dilute the incorporation of (214C) propionate. Incorporation of the 2 and 3 carbon atoms pf propionate were equal; little incorporation of the 1 carbon atom was demonstrable. These results indicate that propionate is an excellent source of 2 carbon units for isoprenoid biosynthesis; the intermediary pathway does not involve a common acetate pool nor can these results be satisfactorily explained by citric acid intermediary metabolism.