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Nicotinamide adenine dinucleotide phosphate, abbreviated NADP [1] [2] or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source'). NADPH is the reduced form, whereas NADP + is the ...
reductase (FNR) that reduces NADP + to NADPH. In cyclic electron transport, electrons from ferredoxin are transferred (via plastoquinol) to a proton pump, cytochrome b 6 f. They are then returned (via plastocyanin) to P700. NADPH and ATP are used to synthesize organic molecules from CO 2. The ratio of NADPH to ATP production can be adjusted by ...
NADP is a reducing agent in anabolic reactions like the Calvin cycle and lipid and nucleic acid syntheses. NADP exists in two forms: NADP+, the oxidized form, and NADPH, the reduced form. NADP is similar to nicotinamide adenine dinucleotide (NAD), but NADP has a phosphate group at the C-2′ position of the adenosyl
The cooperation between Photosystems I and II creates an electron and proton flow from H 2 O to NADP +, producing NADPH needed for glucose synthesis. This pathway is called the 'Z-scheme' because the redox diagram from H 2 O to NADP + via P680 and P700 resembles the letter Z. [11]
Ferredoxin: NADP + reductase is the last enzyme in the transfer of electrons during photosynthesis from photosystem I to NADPH. [2] The NADPH is then used as a reducing equivalent in the reactions of the Calvin cycle. [2] Electron cycling from ferredoxin to NADPH only occurs in the light in part because FNR activity is inhibited in the dark. [11]
The electron is eventually used to reduce the coenzyme NADP with an H + to NADPH (which has functions in the light-independent reaction); at that point, the path of that electron ends. The cyclic reaction is similar to that of the non-cyclic but differs in that it generates only ATP, and no reduced NADP (NADPH) is created.
NADP + + 2H + + 2e-→ NADPH + H + This consumes the H + ions produced by the splitting of water, leading to a net production of 1/2O 2, ATP, and NADPH + H + with the consumption of solar photons and water. The concentration of NADPH in the chloroplast may help regulate which pathway electrons take through the light reactions.
The electrons from the initial light reaction reach Photosystem I, then are raised to a higher energy level by light energy and then received by an electron acceptor and reduce NADP + to NADPH. The electrons lost from Photosystem II get replaced by the oxidation of water, which is "split" into protons and oxygen by the oxygen-evolving complex ...