Metabolism of nicotinamide and nicotinic acid in Neurospora crassa.

Nicotinic acid is outstanding among the B vitamins in that its metabolic fate has been very extensively investigated. These studies, however, have been carried out mostly in higher animals, and they have revealed that (i) N'-methylnicotinamide is, in general, the major end-product of the metabolism of both nicotinic acid and nicotinamide; (ii) nicotinuric acid, the glycine conjugate of nicotinic acid, is also excreted in considerable proportions when nicotinic acid is administered in extraphysiological amounts; (iii) a not insignificant part ofthe vitamin