NADPHReducing coenzymeII, scientific name: reduced nicotinamide adenine dinucleotide phosphatecoenzyme, N meansnicotinamide, A refers toadenineD refers to dinucleotide and P refers to phosphate group.
It plays an important role in chemical reactions in many organismsHydrogen transmitterThe role of is of great significance.It isNicotinamide adenine dinucleotide（NAD+）Phosphorylated derivatives of the ribose ring system at the 2 '- position linked to adenine in the, participate in a variety of anabolic reactions, such as the synthesis of lipids, fatty acids and nucleotides, and can also becarbon dioxideFixed energy supply.These reactions require NADPH as a reducing agent and a donor of hydrogen anion, NADPH is NADP+The restored form of.[1]
Compound Introduction
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NADPH is the ultimate electron acceptor NADP+The product of receiving electrons.
NAD+And NADP+: Nicotinamide adenine dinucleotide (NAD+, coenzyme I) and nicotinamide adenine dinucleotide phosphate (NADP+, coenzyme II, is the oxidized form of NADPH).NAD+And NADP+The coenzyme, which is mainly used as dehydrogenase, plays the role of hydrogen transmitter in enzymatic reaction.
NADPH is usually used as a reducing agent for biosynthesis, and cannot directly enter the respiratory link for oxidation.Only under the action of special enzymes, H on NADPH is transferred to NAD+And then enter the respiratory chain in the form of NADH.
NADPH is formed in the stage of photosynthetic photoreaction, enters the carbon reaction together with ATP, and participates in COtwoFixation of.NADPH is formed on thylakoid membrane of chloroplast.
PEP is the abbreviation of phosphoenolpyruvate, which is an important intermediate product in glycolysis and is produced in the light reaction stage (main chemical formula: NADP++ 2e-+ 2H+→ NADPH + H+）, which provides energy and corresponding enzymes (PEP condensation enzyme) for the carbon reaction stage, and is also used by plants totwoFixed compound.[2]
Related reactions
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NADPH, as a hydrogen donor, can participate in various metabolic reactions in the body:
(1) NADPH is a hydrogen donor for many anabolism in the body, includingDihydrofolate、Tetrahydrofolate, L-malic acid to pyruvate, heme to bilirubin, monooxygenase system, sphingosine, cholesterol, fatty acid, corticosteroids and sex hormonesbiosynthesis；
(2) NADPH+H * participates in the hydroxylation reaction in vivo, and participates in theBiotransformation；
(3) NADPH is used to maintainglutathione(GSH) as GSHreductaseThe coenzyme ofReducibilityThe content of GSH plays an important role.
Generation and type
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Formation of [H] in photosynthesis
Photosynthesis diagram
During the photoreaction stage of photosynthesis, the H produced during water photolysis+With NADP+(Oxidative coenzyme II) reacts as follows under the action of corresponding enzymes: NADP++ H+→ NADPH。
The NADPH generated by the reaction is the [H] in photosynthesis. The two are the same substance, but they are given different expressions based on the different cognitive abilities of students at different learning stages.
Formation and types of [H] in respiration
The first stage of respiration（Aerobic respirationandAnaerobic respirationThe first stage of is the same)Cytoplasmic matrixUnder the action of related enzymes, a small amount of [H] is generated, and the reaction formula (glucose asRespiratory substrateWhen) is: CsixHtwelveOsix(glucose) → 2 CthreeHfourOthree(Pyruvate)+4 [H]+2 ATP.
Diagram of aerobic respiration
The second stage of aerobic respiration ismitochondrionUnder the action of corresponding enzymes in the matrix, the reaction formula is: 2CthreeHfourOthree(Pyruvate)+6 HtwoO → 20 [H]+ 6 COtwo+ 2 ATP。
Although [H] appears in the above two reaction formulas, it includes two different substances, namely NADH（Reduced coenzyme I）And FADHtwo（Reduced flavase）。
According to the above analysis, [H] in photosynthesis is NADPH;[H] in respiration is not NADPH, but NADH and FADHtwo；[H] Including different types ofReduced hydrogenTherefore, [H] cannot be simply considered as NADPH.Of course, although the types of [H] are different, their targets are also different (NADPH targets three carbon compounds, generally written as Cthree, NADH and FADHtwoThe target is Otwo）, but they are all strongReducibilityMatter, from this point of view, can be collectively referred to as [H].[1]
synthesis
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By NAD+staykinaseγ - phosphoric acid receiving ATP under catalysisGroupAnd get.
BotanychloroplastMedium, photosynthesisPhotoreactionThe last step of the electronic chain is NADP+As raw materialFerredoxin-NADP+reductaseAnd produce NADPH.The generated NADPH is thenDark reactionIt is used for carbon dioxide assimilation.
For animals,Pentose phosphate pathwayThe oxidation phase of NADPH is the main source of NADPH in cells, which can produce 60% of the required NADPH (also called [H]).[2]
Related research
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On June 22, 2023, the team of University of Science and Technology of China published a research paper on Nature Metabolism online entitled "A mitotic NADPH upstream promotes chromosome progression and tumour progress in aneuploid cancer cells". This research found that the rise of mitotic specific nicotinamide adenine dinucleotide phosphate (NADPH) is necessary for tumor progression.Specifically, NADPH is produced by glucose 6-phosphate dehydrogenase (G6PD) during mitosis, which neutralizes the elevated reactive oxygen species (ROS) and prevents ROS mediated mitotic kinase inactivation and chromosome misseparation.The mitotic activation of G6PD depends on the phosphorylation of its co chaperone protein BAG3 at threonine 285, which leads to the dissociation of inhibitory BAG3.The results showed that blocking BAG3T285 phosphorylation could induce tumor inhibition.
