Biological Deamidation of Nicotinamide in Vertebrates

Abstract

An enzyme bringing about the deamidation of nicotinamide was demonstrated for the first time in lactic acid bacteria¹ and later in yeast² and Mycobacteria ³. Studies in this laboratory have revealed the presence of nicotinamide-deamidating enzymes in Neurospora crassa ⁴ and the insect larva Corcyracephalonica St.⁵ and that the predominant feature of the vitamin metabolism in these organisms is the deamidation of nicotinamide. In the course of a study of the comparative metabolism of the vitamin in a variety of organisms, the liver and the kidney of several vertebrates have been examined for nicotinamide deamidase activity. A cell-free homogenate of the tissue was prepared in ice-cold distilled water and the enzyme activity measured as described earlier⁴. The results are presented in Table 1.