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Purification and Identification of a Nicotinic Acid-Replacing Substance from Vitamin-Free Acid Hydrolyzed Casein

Department of Microbiology, University of Georgia, Athens 30602

M. V. Williams and G. J. Tritz

Department of Microbiology and Immunology, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501

C. J. Washam

VITEX/R & H Division, Mallinckrodt, Inc., St. Louis, MO 63134

ABSTRACT

A commercial preparation of vitamin-free acid-hydrolyzed casein (casamino acids) contains a growth factor that substitutes for nicotinic acid in nicotinamide adenine dinucleotide auxotrophs of Escherichia coli. This replacing factor was purified by a combination of ethanol extraction, descending partition chromatography, gel permeation chromatography, and crystallization. Structural analysis by mass spectrometry and infrared spectroscopy indicated that the compound has a mass of 368 daltons and contains six types of radicals. A possible structure is presented.