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ß-Hydroxybutyrate Dehydrogenase Activity in Liver and Liver Tumors¹

The Fels Research Institute and Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, and The National Cancer Institute, Bethesda, Maryland 20014

D(-)-ß-Hydroxybutyrate dehydrogenase (EC 1.1.1.30) was assayed in rat liver under various dietary conditions and in a series of liver tumors of varying growth rates and degrees of differentiation. The liver enzyme activity, at about 16 units/gm tissue, was not affected appreciably by drastic dietary alterations. The enzyme was present in a series of slow-growing, well-differentiated hepatic carcinomas, though at levels of 0.1 to 0.3 that of liver, and was very low in several rapidly growing, poorly differentiated tumors, including the Novikoff hepatoma.

Like the liver enzyme, the tumor enzyme was tightly bound to mitochondria. Both were released in a particulate form capable of transferring electrons from substrate to exogenous nicotinamide adenine dinucleotide or its reduced form by sonic treatment or osmotic alteration, but could also be solubilized, though with considerable loss of activity, by treatment with 0.3% cholate. The soluble enzymes did not require lecithin and were not activated by this substance, in contrast with previous data on the soluble beef-heart dehydrogenase. It was eluted rapidly from Sephadex G-200 as a single band, indicating a molecular weight near 200,000. Both the soluble and particle-bound forms of the liver and tumor enzymes had similar kinetic properties, thermal stability, and pH optima, and it is assumed that they are identical.

¹ This work was aided by Grants CA-07174 and AM-05487 from the NIH, and The American Cancer Society Grant P-202.

² Present address: Clinical Research Training Unit, Yale University School of Medicine, New Haven, Connecticut.

Received 2/ 1/67. Accepted 4/ 4/67.