Two Forms of Acetoacetyl Coenzyme A Thiolase in Yeast

摘要: Abstract Two forms of acetoacetyl-CoA thiolase with different properties have been found in Saccharomyces cerevisiae. The enzyme isoelectric point pH 5.3 (thiolase 5.3) is the cytosol while that 7.8 7.8) occurs mitochondria. When yeast are grown on glucose under aerobic conditions, activity shows two increases during growth period. Early log phase, there an increase which subsequently reaches a plateau level. A second at mid-log phase attains peak value before decaying late to stationary phase. biphasic curve also observed anaerobic or galactose, indicating removal catabolite repression by unrelated rise midlog growth. method for distinguishing activities both was developed. early contains predominantly 7.8, due 5.3. Growth provides higher levels mitochondria indicated increased activity. Since same appears growth, it indicates located promitochondria. Yeast aerobically presence d-threochloramphenicol, inhibitor mitochondrial development, exhibited no activity, expression this related development. Thiolase not affected. possibility controls level and acetyl-CoA, negative positive effectors pyruvic carboxylase, discussed.