dimers of nicotinamide adenine dinucleotide : new evidence for the structure and involvement in an enzymatic redox process

The compn. and structure of the product from the known electrochem. dimerization of NAD were conclusively demonstrated. A detailed anal. of the 1H and 13C NMR spectra led to the conclusion that the product contains 3 diastereoisomeric dimers of the 4,4'-tetrahydrobipyridyl type. Furthermore, the cytoplasmic fraction obtained from a std. mitochondrial prepn. of rat liver catalyzed the O2 uptake by the dimers. A 1:1 molar ratio of the reagents in the redox process is indicated by manometric data on O2 uptake complemented by spectrophotometric anal. of the oxidized substrates, suggesting that H2O2 is the redn. product. NAD was identified as the oxidn. product by an enzymic method.