Brain Acyl‐coenzyme a Hydrolase: Distribution, Purification and Properties¹

Rat brain acyl‐CoA hydrolase enzymes which hydrolyse C 2 , C 4 , C 8 and C 16 derivatives were localized primarily in the soluble, 144,000 g , supernatant fluid. With octanoyl‐CoA as substrate, long‐chain acyl‐CoA hydrolase activity was greater in the pons, medulla and midbrain than in the cerebral cortex and caudate nucleus. The long‐chain acyl‐CoA hydrolase enzyme was purified from bovine brain stems to a specific activity of 4‐61 n mol of palmitoyl‐CoA hydrolysed per min per mg protein. The K m values for palmitoyl‐CoA and octanoyl‐CoA were 5 μ m and 14 μ / m , respectively. Activity of the enzyme was inhibited by bovine serum albumin and ρ ‐chloromercuribenzoate. The partially purified enzyme protein was found to have approximately eight titratable sulphydryl residues per 10 5 g of protein. Studies of the molecular weight of the enzyme indicated the presence of associated and dissociated forms with molecular weights of approximately 96,000 and 46,000 respectively.