IMMUNOELECTRON MICROSCOPIC LOCALIZATION OF THIOLASES, BETA-OXIDATION ENZYMES OF AN N-ALKANE-UTILIZABLE YEAST, CANDIDA-TROPICALIS

The location of acetoacetyl-CoA thiolase (T-I) and 3-ketoacyl-CoA thiolase (T-III), enzymes of the fatty acid-beta-oxidation system, was studied in n-alkane-grown Candida tropicalis cells by immunoelectron microscopy using a post-embeddiug method with colloidal gold conjugated IgG. The deposition of gold particles for T-I was detected in the microbodies and cytoplasm and that of gold particles for T-III specifically in the microbodies. The double labeling technique confirmed that T-I and T-III occurred concurrently in a microbody and T-I also in cytoplasm. These results were consistent with the biochemical data based on subcellular fractionation and indicated that the yeast-beta-oxidation system operates efficiently only in the microbodies.