NADPH-NADP+, hydrogen transfer system

Fig. 10. Hydrogen donor systems for ribonucleotide reduction. Enzyme reactions are I thioredoxin reductase (EC 1.6.4.5) II ribonucleotide reductase (EC 1.17.4) III glutathione reductase (EC 1.6.4.2). GSH, GSSG reduced and oxidized glutathione NADPH, NADP reduced and oxidized nicotinamide adenine dinucleotide phosphate coenzymes. The hydrogen transfer chain is continued in Fig. II...

Nicotinamide functions in the animal body as the active group of two important coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).These coenzymes are involved in the mechanism of hydrogen transfer in living cells (see Chapter 9) NAD is involved in the oxidative phosphorylation system, the tricyclic acid (TCA) cycle and the metabolism of many molecules, including pyruvate, acetate, (3-hydroxy-butyrate, glycerol, fatty acids and glutamate NADPH is the hydrogen acceptor in the pentose phosphate pathway. 

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