Nicotineamide adenine dinucleotide

The oxidations are performed in aqueous buffer solution at pH 9.0 with less than stoichiometric amounts of nicotineamide adenine dinucleotide (NAD+) as coenzyme, which is expensive and therefore must be recycled. This can be done in such oxidations in several ways. The simplest is to simultaneously oxidize the reduced nicotineamide adenine dinucleotide formed with a stoichiometric amount (based on the diol) of inexpensive flavin adenine mononucleotide (FMN)167. In this manner gram quantities of the corresponding lactone may be readily obtained scaling up the reaction, however, seems to be a problem167. 

A more efficient system which allows the use of catalytic amounts of nicotineamide adenine dinucleotide and flavin adenine mononucleotide and allows the reaction to be efficiently scaled up, utilizes a catalytic recycling system. Flavin adenine mononucleotide (FMN) reductase (E.C. 1.6.8.1) is used to catalyze the oxidation of reduced nicotineamide adenine dinucleotide by FMN under formation of reduced flavin adenine mononucleotide which in turn is oxidized in both versions to flavin adenine mononucleotide by oxygen169. 

NADH Nicotineamide adenine dinucleotide reduced form. EDTA Ethylenediamine tetraacetic acid. RSH Mercaptoethanol. ZnTPP Zinc tetraphenylporphyrin. ZnTMPyP Zinc tetrakis(4-methylpyridyl)porphyrin. ZnTPPS Zinc tetraphenylporphyrin tetrasulfomate. 

In photosynthesis, light energy is trapped and converted to chemical energy as reduced coenzymes (e.g., nicotineamide-adenine dinucleotide phosphate [NADPH]), triphosphates (e.g., ATP), and 02. Oxygen is a poisonous waste product in plants, although they also need some oxygen in mitochondrial respiration. 

Michaelis et al. 16, 17) have estimated Ei and > for several molecules by analyzing the potentiometric titration curve. This method can be applied only to redox systems which give a large equilibrium concentration of semiquinone, usually for systems for which > 0.01. Direct estimation of semiquinone concentration by ESR (electron spin resonance) is about 10 times more sensitive for the Kg estimation than analysis of titration curves. Some values are shown in Table I. The Kg for NADH (reduced form of nicotineamide adenine dinucleotide) is too small to be measured even by ESR, and only an approximate upper limit is given. 

In order to restart biological oxidation NADPH (or the very similar NADH -nicotineamide adenine dinucleotide) has to be converted back to its oxidized form NADP" (NAD" ) by releasing two electrons to an electron acceptor. In humans... 

The left half-cell is the one supplying electrons to the process NADPH. Yes, the reduced form of nicotineamide adenine dinucleotide phosphate is the zinc electrode in the Daniell cell, and we re-write its reductive half-reaction ... 

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