Degradation of cholesterol to propionic acid by rat liver peroxisomes

Under standard assay conditions peroxisomes were found to contain less than 5% of the liver's cholesterol degradation activity. The remainder of the activity was localized in the mitochondria. When CaCl₂ was added to the standard assay mixture, peroxisomal cholesterol degradation activity increased to 34%. These results suggest that peroxisomes are capable of cholesterol catabolism, with the assay conditions used invitro determining the relative organelle contribution.