Synthesis and properties of (4‐13C)NAD+

Abstract
Starting from (13C)formic acid, acetone and cyanoacetamide samples of (4‐13C)nicotinic acid and (4‐13C)‐nicotinamide were synthesised in an overall and additive yield of 11%.1H‐NMR and mass spectroscopy showed 90% enrichment of 13C in the expected position. NADase‐catalysed exchange between thionicotinamide–adenine dinucleotide and (4‐13C)nicotinamide furnished (4‐13C)NAD+ which was purified, characterized and quantified by 1H‐NMR and 13C‐NMR spectroscopy and by enzymic assay. The 13C‐NMR signal of (4‐13C)β‐NAD+ (146.09 ppm) was broadened and shifted (147.83 ppm) upon binding to yeast alcohol dehydrogenase.