Nicotinamide Deamidase from Mammalian Liver.

Previous studies from our laboratory indicated that the initial step in the biosynthesis of nicotinamide adenine dinucleotide from nicotinamide in mammalian liver involves the enzymatic deamidation of nicotinamide to nicotinic acid (1, 2). The nicotinic acid is then converted to NAD via the pathway described by Preiss and Handler, involving the intermediate formation of nicotinic acid mononucleotide and nicotinic acid adenine dinucleotide (3, 4). In the present communication, the solubilization and partial purification of nicotinamide deamidase from rat and rabbit liver microsomes is described, together with some properties of the enzyme from both species.