Nicotinamide adenine dinucleotide phosphate
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3D model (
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ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard
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100.000.163 |
MeSH | NADP |
PubChem CID
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Properties | |
C21H29N7O17P3 | |
Molar mass | 744.416 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Nicotinamide adenine dinucleotide phosphate, abbreviated NADP+ or, in older notation, TPN (triphosphopyridine nucleotide), is a
NADP+ differs from
Biosynthesis
NADP+
In general, NADP+ is synthesized before NADPH is. Such a reaction usually starts with
NADPH
NADPH is produced from NADP+. The major source of NADPH in animals and other non-photosynthetic organisms is the pentose phosphate pathway, by glucose-6-phosphate dehydrogenase (G6PDH) in the first step. The pentose phosphate pathway also produces pentose, another important part of NAD(P)H, from glucose. Some bacteria also use G6PDH for the Entner–Doudoroff pathway, but NADPH production remains the same.[1]
Ferredoxin–NADP+ reductase, present in all domains of life, is a major source of NADPH in photosynthetic organisms including plants and cyanobacteria. It appears in the last step of the electron chain of the light reactions of photosynthesis. It is used as reducing power for the biosynthetic reactions in the Calvin cycle to assimilate carbon dioxide and help turn the carbon dioxide into glucose. It has functions in accepting electrons in other non-photosynthetic pathways as well: it is needed in the reduction of nitrate into ammonia for plant assimilation in nitrogen cycle and in the production of oils.[1]
There are several other lesser-known mechanisms of generating NADPH, all of which depend on the presence of
NADPH can also be generated through pathways unrelated to carbon metabolism. The ferredoxin reductase is such an example.
Like
Function
NADPH provides the reducing agents, usually hydrogen atoms, for biosynthetic reactions and the
The NADPH system is also responsible for generating free radicals in immune cells by NADPH oxidase. These radicals are used to destroy pathogens in a process termed the respiratory burst.[11] It is the source of reducing equivalents for
.Stability
NADH and NADPH are very stable in basic solutions, but NAD+ and NADP+ are degraded in basic solutions into a fluorescent product that can be used conveniently for quantitation. Conversely, NADPH and NADH are degraded by acidic solutions while NAD+/NADP+ are fairly stable to acid.[12]
Enzymes that use NADP(H) as a coenzyme
- Adrenodoxin reductase: This enzyme is present ubiquitously in most organisms.[13] It transfers two electrons from NADPH to FAD. In vertebrates, it serves as the first enzyme in the chain of mitochondrial P450 systems that synthesize steroid hormones.[14]
Enzymes that use NADP(H) as a substrate
In 2018 and 2019, the first two reports of enzymes that catalyze the removal of the 2' phosphate of NADP(H) in eukaryotes emerged. First the
References
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- ^ Palmer, Michael. "10.4.3 Supply of NADPH for fatty acid synthesis". Metabolism Course Notes. Archived from the original on 6 June 2013. Retrieved 6 April 2012.
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- ^ ISBN 978-0-07-182537-5.
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- S2CID 7120148.
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- doi:10.1101/325266.
- PMID 31147539.
- PMID 31147539.