Kinetic characterization of a cytosolic L-β-hydroxybutyrate dehydrogenase from hepatopancreas of a terrestrial snail,Cepaea nemoralis

✍ Scribed by Stuart, J. A.; Ballantyne, J. S.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 98 KB
• Volume: 278
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/(sici)1097-010x(19970615)278:3<140::aid-jez3>3.0.co;2-o

✦ Synopsis

The hepatopancreas of the terrestrial gastropod Cepaea nemoralis has a cytoplasmic β-hydroxybutyrate dehydrogenase specific for L-β-hydroxybutyrate. No dehydrogenation of Dβ-hydroxybutyrate by the enzyme was detected under our experimental conditions. The apparent K m for L-β-hydroxybutyrate is similar to K m values for D-β-hydroxybutyrate determined for the mitochondrial D-β-hydroxybutyrate dehydrogenase from other sources. The apparent K m for acetoacetate of the cytoplasmic L-β-hydroxybutyrate dehydrogenase is an order of magnitude greater than that of the mitochondrial enzyme. The cytosolic enzyme is markedly sensitive to pH, with opposite effects on V max in the forward and reverse directions. L-β-hydroxybutyrate dehydrogenase kinetics are also affected by adenosine phosphates and acetoacetyl-CoA. The kinetic properties of the enzyme suggest that while L-β-hydroxybutyrate dehydrogenation appears to be favoured, it could catalyze the production of L-β-hydroxybutyrate from acetoacetate in the hepatopancreas of estivating terrestrial snails.