Nicotinamide-adenine dinucleotide phosphate formula

An important aspect of enzymatic oxidation-reduction reactions involves the transfer of hydrogen atoms. This transfer is mediated by coenzymes (substances that act together with enzymes) nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These two species pick up H atoms to produce NADH and NADPH, respectively, both of which can function as hydrogen atom donors. Another pair of species involved in oxidation-reduction processes by hydrogen atom transfer consists of flavin adenine triphosphate (FAD) and its hydrogenated form FADH2. The structural formulas of NAD and its cationic form, NAD+, are shown in Figure 4.7. 

As we pointed out, however, the electrons will not flow unless they have someplace to go. In the light phase of photosynthesis, the electrons moving down the electron transport chain are taken up by nicotinamide adenine dinucleotide phosphate, a molecule with nearly as many symbols in its formula as letters in its unwieldy name. Luckily, it suffices to refer to this entity by its initials, NADP+, a practice common in the complicated world of biochemistry. 

The reactions of photosynthesis can be carried out in the dark by cells of green plants if they are provided with a supply both of ATP and of another substance, NADPH (reduced nicotinamide-adenine dinucleotide phosphate), which has the formula... 

The formation of nicotinic acid, as important as it is for the synthesis of the two coenzymes nicotinamide-adenine dinucleotide and its phosphate (formulas in Chapt. VI-4), seems to be only a sidepath. The main degradation probably passes from the unstable, unsaturated aminoaldehyde through isomerization to the imino compound and through hydrolysis to the k to compound. The jS-decarboxylation of the latter results in an a-keto aldehyde with six C atoms which is further broken down to glutarate. 

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