Diphosphopyridine nucleotide, reaction with enzymes

It would be well to point out a few examples which illustrate the overlap of asymmetric reduction studies and molecular biochemistry. Diphosphopyridine nucleotide (DPN) and triphospho-pyridine nucleotide (TPN) are important coenzymes in biochemical oxidation reduction reactions. Certain enzymes function as catalysts for the reversible transfer of hydrogen between these nucleotides and a substrate for which the enzyme is specific. For example, DPN and the enzyme, alcohol dehydrogenase (ADH), form a redox system with ethanol. Using deuterium labeled reducing agent and substrate, Westheimer, Vennesland,... 

With our sensitive spectrophotometric methods (11,12,17) we have shown how the reaction velocity constants for peroxidase action can be measured directly from the kinetics of formation and disappearance of the enzyme-substrate complex. This is perhaps the most elegant and incisive method of assay and can now be successfully applied not only to hemo-proteins but also to diphosphopyridine nucleotide enzymes. The detaUs of the methods lie outside the scope of this review and are available in detail elsewhere (3,6). 

The mechanism of synthesis of flavin adenine dinucleotide was established by Schrecker and Komberg 1S6) with a purified enzyme from brewer s yeast. The coenzyme is formed by a reaction analogous to the synthesis of diphosphopyridine nucleotide (1S7). 

---