Nicotinamide adenine dinucleotide phosphate
Encyclopedia
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation (triphosphopyridine nucleotide), is a coenzyme used in anabolic reactions, such as lipid
and nucleic acid
synthesis, which require NADPH as a reducing agent
.
NADPH is the reduced
form of NADP. NADP differs from NAD in the presence of an additional phosphate group on the 2' position of the ribose
ring that carries the adenine
moiety.
, NADP− is added by ferredoxin-NADP reductase
in the last step of the electron chain of the light reactions of Photosynthesis
. The NADPH produced is then used as reducing power for the biosynthetic reactions in the Calvin Cycle
of photosynthesis. In its energized state, it is NADPH, now holding an extra electron. It is used primarily to create the proton gradient in chloroplasts during the light-dependent reactions.
is the major source of NADPH in cells, producing approximately 60% of the NADPH required.
NADPH provides the reducing equivalents for biosynthetic reactions and the oxidation-reduction involved in protecting against the toxicity of ROS (reactive oxygen species
), allowing the regeneration of GSH (reduced glutathione).
NADPH is also used for anabolic pathways, such as lipid synthesis, cholesterol synthesis, and fatty acid chain elongation
.
The NADPH system is also responsible for generating free radicals in immune cells. These radicals are used to destroy pathogens in a process termed the respiratory burst
.
It is the source of reducing equivalents for cytochrome P450 hydroxylation
of aromatic compounds, steroid
s, alcohol
s, and drug
s.
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
and nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
synthesis, which require NADPH as a reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...
.
NADPH is the reduced
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
form of NADP. NADP differs from NAD in the presence of an additional phosphate group on the 2' position of the ribose
Ribose
Ribose is an organic compound with the formula C5H10O5; specifically, a monosaccharide with linear form H––4–H, which has all the hydroxyl groups on the same side in the Fischer projection....
ring that carries the adenine
Adenine
Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
moiety.
In plants
In chlorophyllChlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
, NADP− is added by ferredoxin-NADP reductase
Ferredoxin-NADP+ reductase
In enzymology, a ferredoxin-NADP reductase abbreviated FNR, is an enzyme that catalyzes the chemical reactionThe 3 substrates of this enzyme are reduced ferredoxin, NADP, and H, whereas its two products are oxidized ferredoxin and NADPH...
in the last step of the electron chain of the light reactions of Photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
. The NADPH produced is then used as reducing power for the biosynthetic reactions in the Calvin Cycle
Calvin cycle
The Calvin cycle or Calvin–Benson-Bassham cycle or reductive pentose phosphate cycle or C3 cycle or CBB cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms...
of photosynthesis. In its energized state, it is NADPH, now holding an extra electron. It is used primarily to create the proton gradient in chloroplasts during the light-dependent reactions.
In animals
The oxidative phase of the pentose phosphate pathwayPentose phosphate pathway
The pentose phosphate pathway is a process that generates NADPH and pentoses . There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars...
is the major source of NADPH in cells, producing approximately 60% of the NADPH required.
NADPH provides the reducing equivalents for biosynthetic reactions and the oxidation-reduction involved in protecting against the toxicity of ROS (reactive oxygen species
Reactive oxygen species
Reactive oxygen species are chemically reactive molecules containing oxygen. Examples include oxygen ions and peroxides. Reactive oxygen species are highly reactive due to the presence of unpaired valence shell electrons....
), allowing the regeneration of GSH (reduced glutathione).
NADPH is also used for anabolic pathways, such as lipid synthesis, cholesterol synthesis, and fatty acid chain elongation
Fatty acid synthesis
Fatty acid synthesis is the creation of fatty acids from acetyl-CoA and malonyl-CoA precursors through action of enzymes called fatty acid synthases...
.
The NADPH system is also responsible for generating free radicals in immune cells. These radicals are used to destroy pathogens in a process termed the respiratory burst
Respiratory burst
Respiratory burst is the rapid release of reactive oxygen species from different types of cells....
.
It is the source of reducing equivalents for cytochrome P450 hydroxylation
Hydroxylation
Hydroxylation is a chemical process that introduces a hydroxyl group into an organic compound. In biochemistry, hydroxylation reactions are often facilitated by enzymes called hydroxylases. Hydroxylation is the first step in the oxidative degradation of organic compounds in air...
of aromatic compounds, steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
s, alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s, and drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
s.