Abstract
Auxotrophs of Escherichia coli defective in biosynthesis of nicotinamide adenine dinucleotide are able to proliferate in a minimal medium containing either nicotinic acid or vitamin-free acid hydrolyzed casein (casamino acids). The active component in acid-hydrolyzed casein is not nicotinic acid or nicotinamide as determined by partition chromatography, analysis for teritary and quarternary amines, and the Mueller and Fox reaction for nicotinic acid. It is not affected by proteinases. The activity of acid-hydrolyzed casein is lost by acid or alkaline hydrolysis, ashing, and charcoal filtration. The active factor has a molecular weight of less than 500 and is slightly soluble in n-butanol. It is insoluble in ether and chloroform.
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