Novel aspects of the activities and subcellular distribution of enzymes ofketone body metabolism in the liver and kidney of the goldfish, Carassius auratus

rc1rc1The metabolic organization of ketone body metabolism of liver and kid ney of the goldfish Carassius auratus was assessed by measuring maximal act ivities, subcellular distribution, and stereoisomer preference of ketone bo dy enzymes. These determinations indicate that the organization of ketone b ody metabolism in liver and kidney of goldfish differs from that of mammals in some respects. All the enzymes of ketone body metabolism were present i n liver and kidney of goldfish, with the exception of hydroxymethylglutaryl -CoA (HMG-CoA) synthetase, which was not detected in liver. Two forms of be ta-hydroxybutyrate dehydrogenase (beta HBDH) with different stereospecifici ty for beta-hydroxybutyrate (D- and L-beta-hydroxybutyrate) were detectable in liver and kidney. All of the ketone body enzymes measured in Liver were mainly in the mitochondrial fraction, with the exception of D- and L-beta HBDH, which were cytosolic. In kidney, HMG-CoA synthase, together with HMG- CoA lyase and acetoacetyl CoA thiolase (AcoAT), were found mainly in the mi tochondrial fraction. L-beta HBDH was mainly cytosolic in kidney, but by co ntrast with liver, D-beta HBDH was mainly found in the mitochondria, and SK T was distributed in both the mitochondrial and cytosolic compartments. (C) 2000 Wiley-Liss, Inc.