Molecular Pharmacology, Vol 3, 233-247, Copyright © 1967 by the American Society for Pharmacology and Experimental Therapeutics

Purification and Some Characteristics of an ,-Unsaturated Ketone Reductase from Dog Erythrocytes and Human Liver

¹ Department of Pharmacology, School of Medicine, Loma Linda University, Loma Linda, California 92354

An enzyme which catalyzes the reduction of ,-unsaturated ketones by NADPH has been purified from dog erythrocytes and human liver. The enzyme was relatively stable at low temperatures but rapidly inactivated above 50°. The pH optimum was broad with a range of 5.5-7.5. Among the possible substrates tested most, but not all, unsaturated ketones were attacked by the enzyme; none of the saturated aldehydes and ketones were attacked, however, nor were any of the unsaturated compounds which lacked a keto group. Michaelis constants for active substrates were in the vicinity of 10^-4 M. Approximately one molecule of NADPH was oxidized for each molecule of unsaturated ketone reduced. The activity of the enzyme was decreased by the sulfhydryl inhibitors p-chloromercuribenzoate and N-ethylmaleimide. The enzyme has been differentiated from a variety of other enzymes including methemoglobin reductase, glutathione reductase, aldehyde-ketone reductase, aromatic -keto acid reductase, alcohol dehydrogenase, lactic dehydrogenase, NADPH-cytochrome c reductase and fatty acid synthetase, but not from an enzyme previously described as crotonyl CoA reductase.

Note:
ACKNOWLEDGMENTS This investigation was supported in part by Public Health Service Research Grant CY-4712 from the National Cancer Institute and Grant AM-08610 from the National Institute of Arthritis and Metabolic Diseases. The skillful assistance of W. C. Patton and D. E. Ewing, while supported by Southern California Diabetes Association Summer Fellowships, is gratefully acknowledged. The skillful assistance of H. Heidar while supported by a summer fellowship from the General Research Support Grant to the School of Medicine, Loma Linda University, by the National Institute of General Medical Sciences, is also gratefully acknowledged.

This article has been cited by other articles:

				S. Kitamura, Y. Kohno, Y. Okamoto, M. Takeshita, and S. Ohta Reductive Metabolism of an alpha ,beta -Ketoalkyne, 4-Phenyl-3-Butyn-2-One, by Rat Liver Preparations Drug Metab. Dispos., April 1, 2002; 30(4): 414 - 420. [Abstract] [Full Text] [PDF]

				J.-M. Sauer, R. L. Smith, J. Bao, M. J. Kattnig, R. K. Kuester, T. D. McClure, M. Mayersohn, and I. G. Sipes Oral and Topical Absorption, Disposition Kinetics, and the Metabolic Fate of trans-Methyl Styryl Ketone in the Male Fischer 344 Rat Drug Metab. Dispos., June 1, 1997; 25(6): 732 - 739. [Abstract] [Full Text]

				N. Bachur Cytoplasmic aldo-keto reductases: a class of drug metabolizing enzymes Science, August 13, 1976; 193(4253): 595 - 597. [Abstract] [PDF]