Two Cases of ß-KetothioIase Deficiency: A Comparison

At least three isoenzymes of s-ketothiolase exist in human fibroblasts: (1) a mitochondrial’ branched chain’ s-ketothiolase (MBK) (EC 2.3.1.9) which can thiolyse 2-methylacetoacetyl CoA and acetoacetyl CoA., (2) a mitochondrial’ straight chain’ s-ketothiolase (MSK) (EC 2.3.1.16) which can thiolyse long and medium straight-chain 3-ketoacyl CoAs and, to a lesser extent, acetoacetyl CoA and (3) a cytosolic s-ketothiolase (CK) (EC 2.3.1.9) specific for acetoacetyl CoA.