A phosphate is a chemical derivative of phosphoric acid. The phosphate ion (PO3−
) is an inorganic chemical, the conjugate base that can form many different salts. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Of the various phosphoric acids and phosphates, organic phosphates are important in biochemistry and biogeochemistry (and, consequently, in ecology), and inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry.[2] At elevated temperatures in the solid state, phosphates can condense to form pyrophosphates.

In biology, adding phosphates to—and removing them from—proteins in cells are both pivotal in the regulation of metabolic processes. Referred to as phosphorylation and dephosphorylation, respectively, they are important ways that energy is stored and released in living systems.

Stereo skeletal formula of phosphate
Aromatic ball and stick model of phosphate
Space-filling model of phosphate
Systematic IUPAC name
3D model (JSmol)
MeSH Phosphates
Molar mass 94.9714 g mol−1
Conjugate acid Hydrogen phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chemical properties

Phosphate Group
This is the structural formula of the phosphoric acid functional group as found in weakly acidic aqueous solution. In more basic aqueous solutions, the group donates its two hydrogen atoms and ionizes as a phosphate group with a negative charge of 2. [3]

The phosphate ion is a polyatomic ion with the empirical formula PO3−
and a molar mass of 94.97 g/mol. It consists of one central phosphorus atom surrounded by four oxygen atoms in a tetrahedral arrangement. The phosphate ion carries a −3 formal charge and is the conjugate base of the hydrogen phosphate ion, HPO2−
, which is the conjugate base of H
, the dihydrogen phosphate ion, which in turn is the conjugate base of H
, phosphoric acid. A phosphate salt forms when a positively charged ion attaches to the negatively charged oxygen atoms of the ion, forming an ionic compound.

Many phosphates are not soluble in water at standard temperature and pressure. The sodium, potassium, rubidium, caesium, and ammonium phosphates are all water-soluble. Most other phosphates are only slightly soluble or are insoluble in water. As a rule, the hydrogen and dihydrogen phosphates are slightly more soluble than the corresponding phosphates. The pyrophosphates are mostly water-soluble. Aqueous phosphate exists in four forms:

  • In strongly basic conditions, the phosphate ion (PO3−
    ) predominates,
  • In weakly basic conditions, the hydrogen phosphate ion (HPO2−
    ) is prevalent.
  • In weakly acidic conditions, the dihydrogen phosphate ion (H
    ) is most common.
  • In strongly acidic conditions, trihydrogen phosphate (H
    ) is the main form.


Phosphoric acid



Dihydrogen phosphate



Hydrogen phosphate




More precisely, considering these three equilibrium reactions:

⇌ H+ + H
⇌ H+ + HPO2−
⇌ H+ + PO3−

the corresponding constants at 25 °C (in mol/L) are (see phosphoric acid):

      (pKa1 ≈ 2.12)
      (pKa2 ≈ 7.21)
      (pKa3 ≈ 12.67)
Phosphoric acid speciation


The speciation diagram obtained using these pK values shows three distinct regions. In effect, H
, H
and HPO2−
behave as separate weak acids because the successive pK values differ by more than 4. For each acid, the pH at half-neutralization is equal to the pK value of the acid. The region in which the acid is in equilibrium with its conjugate base is defined by pH ≈ pK ± 2. Thus, the three pH regions are approximately 0–4, 5–9 and 10–14. This is a simplified model, assuming a constant ionic strength. It will not hold in reality at very low and very high pH values.

For a neutral pH, as in the cytosol, pH = 7.0

so that only H
and HPO2−
ions are present in significant amounts (62% H
, 38% HPO2−
. Note that in the extracellular fluid (pH = 7.4), this proportion is inverted (61% HPO2−
, 39% H

Phosphate can form many polymeric ions such as pyrophosphate), P
, and triphosphate, P
. The various metaphosphate ions (which are usually long linear polymers) have an empirical formula of PO
and are found in many compounds.

Biochemistry of phosphates

In biological systems, phosphorus is found as a free phosphate ion in solution and is called inorganic phosphate, to distinguish it from phosphates bound in various phosphate esters. Inorganic phosphate is generally denoted Pi and at physiological (homeostatic) pH primarily consists of a mixture of HPO2−
and H

Inorganic phosphate can be created by the hydrolysis of pyrophosphate, denoted PPi:

+ H2O ⇌ 2 HPO2−

However, phosphates are most commonly found in the form of adenosine phosphates (AMP, ADP, and ATP) and in DNA and RNA. It can be released by the hydrolysis of ATP or ADP. Similar reactions exist for the other nucleoside diphosphates and triphosphates. Phosphoanhydride bonds in ADP and ATP, or other nucleoside diphosphates and triphosphates, can release high amounts of energy when hydrolyzed which give them their vital role in all living organisms. They are generally referred to as high-energy phosphate, as are the phosphagens in muscle tissue. Compounds such as substituted phosphines have uses in organic chemistry, but do not seem to have any natural counterparts.

The addition and removal of phosphate from proteins in all cells is a pivotal strategy in the regulation of metabolic processes. Phosphorylation and dephosphorylation are important ways that energy is stored and released in living systems. Cells use ATP for this.

Reference ranges for blood tests, showing 'inorganic phosphorus' in purple at right, being almost identical to the molar concentration of phosphate
Reference ranges for blood tests, showing 'inorganic phosphorus' in purple at right, being almost identical to the molar concentration of phosphate

Phosphate is useful in animal cells as a buffering agent. Phosphate salts that are commonly used for preparing buffer solutions at cell pHs include Na2HPO4, NaH2PO4, and the corresponding potassium salts.

An important occurrence of phosphates in biological systems is as the structural material of bone and teeth. These structures are made of crystalline calcium phosphate in the form of hydroxyapatite. The hard dense enamel of mammalian teeth consists of fluoroapatite, a hydroxy calcium phosphate where some of the hydroxyl groups have been replaced by fluoride ions.

Plants take up phosphorus through several pathways: the arbuscular mycorrhizal pathway and the direct uptake pathway.

Occurrence and mining

Phosphate Mine Panorama
Phosphate mine near Flaming Gorge, Utah, 2008
Train loaded with phosphate rock, Metlaoui Tunisia-4298B
Train loaded with phosphate rock, Métlaoui, Tunisia, 2012

Phosphates are the naturally occurring form of the element phosphorus, found in many phosphate minerals. In mineralogy and geology, phosphate refers to a rock or ore containing phosphate ions. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry.[2]

The largest global producer and exporter of phosphates is Morocco. Within North America, the largest deposits lie in the Bone Valley region of central Florida, the Soda Springs region of southeastern Idaho, and the coast of North Carolina. Smaller deposits are located in Montana, Tennessee, Georgia, and South Carolina. The small island nation of Nauru and its neighbor Banaba Island, which used to have massive phosphate deposits of the best quality, have been mined excessively. Rock phosphate can also be found in Egypt, Israel, Western Sahara, Navassa Island, Tunisia, Togo, and Jordan, countries that have large phosphate-mining industries.

Phosphorite mines are primarily found in:

In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years.[4] However, some scientists thought that a "peak phosphorus" will occur in 30 years and Dana Cordell from Institute for Sustainable Futures said that at "current rates, reserves will be depleted in the next 50 to 100 years".[5] Reserves refer to the amount assumed recoverable at current market prices, and, in 2012, the USGS estimated 71 billion tons of world reserves, while 0.19 billion tons were mined globally in 2011.[6] Phosphorus comprises 0.1% by mass of the average rock[7] (while, for perspective, its typical concentration in vegetation is 0.03% to 0.2%),[8] and consequently there are quadrillions of tons of phosphorus in Earth's 3 * 1019 ton crust,[9] albeit at predominantly lower concentration than the deposits counted as reserves from being inventoried and cheaper to extract; if it is assumed that the phosphate minerals in phosphate rock are hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight and if phosphate rock contains around 20% of these minerals, the average phosphate rock has roughly 3.7% phosphorus by weight.

Some phosphate rock deposits, such as Mulberry in Florida,[10] are notable for their inclusion of significant quantities of radioactive uranium isotopes. This syndrome is noteworthy because radioactivity can be released into surface waters[11] in the process of application of the resultant phosphate fertilizer (e.g. in many tobacco farming operations in the southeast US).

In December 2012, Cominco Resources announced an updated JORC compliant resource of their Hinda project in Congo-Brazzaville of 531 Mt, making it the largest measured and indicated phosphate deposit in the world.[12]


The three principal phosphate producer countries (China, Morocco and the United States) account for about 70% of world production.

Production and global reserves of natural phosphate by country in 2015
(USGS, 2016)[13]
Country Production
(millions kg)
Mondial part
Mondial reserves
(millions kg)
 Algeria 1,200 0.54 2,200,000
 Australia 2,600 1.17 1,030,000
 Brazil 6,700 3.00 315,000
 China 100,000 44.83 3,700,000
 Egypt 5,500 2.47 1,250,000
 India 1,100 0.49 65,000
 Iraq 200 0.09 430,000
 Israel 3,300 1.48 130,000
 Jordan 7,500 3.36 1,300,000
 Kazakhstan 1,600 0.72 260,000
 Mexico 1,700 0.76 30,000
 Morocco 30,000 13.45 50,000,000
 Peru 4,000 1.79 820,000
 Russia 12,500 5.60 1,300,000
 Saudi Arabia 3,300 1.48 956,000
 Senegal 1,000 0.45 50,000
 South Africa 2,200 0.99 1,500,000
 Syria 750 0.34 1,800,000
 Togo 1,000 0.45 30,000
 Tunisia 4,000 1.79 100,000
 United States 27,600 12.37 1,100,000
 Vietnam 2,700 1.21 30,000
Other countries 2,600 1.17 380,000
Total 223,000 100 69,000,000


WOA09 sea-surf PO4 AYool
Sea surface phosphate from the World Ocean Atlas
Relationship of phosphate to nitrate uptake for photosynthesis in various regions of the ocean. Note that nitrate is more often limiting than phosphate. See the Redfield ratio.

In ecological terms, because of its important role in biological systems, phosphate is a highly sought after resource. Once used, it is often a limiting nutrient in environments, and its availability may govern the rate of growth of organisms. This is generally true of freshwater environments, whereas nitrogen is more often the limiting nutrient in marine (seawater) environments. Addition of high levels of phosphate to environments and to micro-environments in which it is typically rare can have significant ecological consequences. For example, blooms in the populations of some organisms at the expense of others, and the collapse of populations deprived of resources such as oxygen (see eutrophication) can occur. In the context of pollution, phosphates are one component of total dissolved solids, a major indicator of water quality, but not all phosphorus is in a molecular form that algae can break down and consume.[14]

Calcium hydroxyapatite and calcite precipitates can be found around bacteria in alluvial topsoil.[15] As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates.[15]

Phosphate deposits can contain significant amounts of naturally occurring heavy metals. Mining operations processing phosphate rock can leave tailings piles containing elevated levels of cadmium, lead, nickel, copper, chromium, and uranium. Unless carefully managed, these waste products can leach heavy metals into groundwater or nearby estuaries. Uptake of these substances by plants and marine life can lead to concentration of toxic heavy metals in food products.[16]

See also


  1. ^ "Phosphates – PubChem Public Chemical Database". The PubChem Project. USA: National Center of Biotechnology Information.
  2. ^ a b "Phosphate Primer". Florida Industrial and Phosphate Research Institute. Florida Polytechnic University. Archived from the original on 29 August 2017.
  3. ^ Campbell, Neil A.; Reece, Jane B. (2005). Biology (Seventh ed.). San Francisco, California: Benjamin Cummings. p. 65. ISBN 0-8053-7171-0.
  4. ^ Reilly, Michael (May 26, 2007). "How Long Will it Last?". New Scientist. 194 (2605): 38–9. Bibcode:2007NewSc.194...38R. doi:10.1016/S0262-4079(07)61508-5.
  5. ^ Leo Lewis (2008-06-23). "Scientists warn of lack of vital phosphorus as biofuels raise demand". The Times.
  6. ^ U.S. Geological Survey Phosphate Rock
  7. ^ U.S. Geological Survey Phosphorus Soil Samples
  8. ^ Floor Anthoni. "Abundance of Elements". Retrieved 2013-01-10.
  9. ^ American Geophysical Union, Fall Meeting 2007, abstract #V33A-1161. Mass and Composition of the Continental Crust
  10. ^ Central Florida Phosphate Industry: Environmental Impact Statement. 2. United States. Environmental Protection Agency. 1979.
  11. ^ C. Michael Hogan (2010). Mark McGinley and C. Cleveland (Washington, DC.: National Council for Science and the Environment) (ed.). "Water pollution". Encyclopedia of Earth. Archived from the original on 2010-09-16.
  12. ^ "Updated Hinda Resource Announcement: Now world's largest phosphate deposit (04/12/2012)". Cominco Resources.
  13. ^ USGS Minerals Year Book - Phosphate Rock
  14. ^ Hochanadel, Dave (December 10, 2010). "Limited amount of total phosphorus actually feeds algae, study finds". Lake Scientist. Retrieved June 10, 2012. [B]ioavailable phosphorus – phosphorus that can be utilized by plants and bacteria – is only a fraction of the total, according to Michael Brett, a UW engineering professor ...
  15. ^ a b Schmittner KE, Giresse P (1999). "Micro-environmental controls on biomineralization: superficial processes of apatite and calcite precipitation in Quaternary soils, Roussillon, France". Sedimentology. 46 (3): 463–76. Bibcode:1999Sedim..46..463S. doi:10.1046/j.1365-3091.1999.00224.x.
  16. ^ Gnandi, K.; Tchangbedjil, G.; Killil, K.; Babal, G.; Abbel, E. (March 2006). "The Impact of Phosphate Mine Tailings on the Bioaccumulation of Heavy Metals in Marine Fish and Crustaceans from the Coastal Zone of Togo". Mine Water and the Environment. 25 (1): 56–62. doi:10.1007/s10230-006-0108-4.

External links

Calvin cycle

The calvin cycle, light-independent reactions, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis are the chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. There are three phases to the light-independent reactions, collectively called the Calvin cycle: carbon fixation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration.

This process occurs only when light is available. Plants do not carry out the Calvin cycle during nighttime. They instead release sucrose into the phloem from their starch reserves to provide energy for the plant. This process happens when light is available independent of the kind of photosynthesis (C3 carbon fixation, C4 carbon fixation, and Crassulacean Acid Metabolism (CAM)); CAM plants store malic acid in their vacuoles every night and release it by day to make this process work. They are also known as dark reactions.

Cellular respiration

Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process, as weak so-called "high-energy" bonds are replaced by stronger bonds in the products. Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. Cellular respiration is considered an exothermic redox reaction which releases heat. The overall reaction occurs in a series of biochemical steps, most of which are redox reactions themselves. Although cellular respiration is technically a combustion reaction, it clearly does not resemble one when it occurs in a living cell because of the slow release of energy from the series of reactions.

Nutrients that are commonly used by animal and plant cells in respiration include sugar, amino acids and fatty acids, and the most common oxidizing agent (electron acceptor) is molecular oxygen (O2). The chemical energy stored in ATP (its third phosphate group is weakly bonded to the rest of the molecule and is cheaply broken allowing stronger bonds to form, thereby transferring energy for use by the cell) can then be used to drive processes requiring energy, including biosynthesis, locomotion or transportation of molecules across cell membranes.


Clindamycin is an antibiotic used for the treatment of a number of bacterial infections. These include middle ear infections, bone or joint infections, pelvic inflammatory disease, strep throat, pneumonia, and endocarditis, among others. It can be used against some cases of methicillin-resistant Staphylococcus aureus (MRSA). It may also be used for the treatment of acne. In combination with quinine, it can be used for malaria. It is available by mouth, by injection into a vein, and as a cream to be applied to the skin or in the vagina.Common side effects include nausea, diarrhea, rash, and pain at the site of injection. It increases the risk of hospital-acquired Clostridium difficile colitis about fourfold. Alternative antibiotics may be recommended as a result. It appears to be generally safe in pregnancy. It is of the lincosamide class and works by blocking bacteria from making protein.Clindamycin was first made in 1966 or 1967. It is on the World Health Organization's List of Essential Medicines, which lists the most effective and safe medicines needed in a health system. It is available as a generic medication and is not very expensive. The wholesale cost in the developing world is about US$0.06–0.12 per pill. In the United States, it costs about $2.70 per dose. In 2016, it was the 151st most prescribed medication in the United States, with more than 4 million prescriptions.


A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin (other than liming materials) that is applied to soils or to plant tissues to supply one or more plant nutrients essential to the growth of plants. Many sources of fertilizer exist, both natural and industrially produced.

Glucose-6-phosphate dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) (EC is a cytosolic enzyme that catalyzes the chemical reaction

D-glucose 6-phosphate + NADP+ ⇌ 6-phospho-D-glucono-1,5-lactone + NADPH + H+This enzyme participates in the pentose phosphate pathway (see image), a metabolic pathway that supplies reducing energy to cells (such as erythrocytes) by maintaining the level of the co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). The NADPH in turn maintains the level of glutathione in these cells that helps protect the red blood cells against oxidative damage from compounds like hydrogen peroxide. Of greater quantitative importance is the production of NADPH for tissues involved in biosynthesis of fatty acids or isoprenoids, such as the liver, mammary glands, adipose tissue, and the adrenal glands. G6PD reduces NADP+ to NADPH while oxidizing glucose-6-phosphate.Clinically, an X-linked genetic deficiency of G6PD predisposes a person to non-immune hemolytic anemia.

Glucose-6-phosphate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase deficiency (G6PDD) is an inborn error of metabolism that predisposes to red blood cell breakdown. Most of the time, those who are affected have no symptoms. Following a specific trigger, symptoms such as yellowish skin, dark urine, shortness of breath, and feeling tired may develop. Complications can include anemia and newborn jaundice. Some people never have symptoms.It is an X-linked recessive disorder that results in defective glucose-6-phosphate dehydrogenase enzyme. Red blood cell breakdown may be triggered by infections, certain medication, stress, or foods such as fava beans. Depending on the specific mutation the severity of the condition may vary. Diagnosis is based on symptoms and supported by blood tests and genetic testing.Avoiding triggers is important. Treatment of acute episodes may include medications for infection, stopping the offending medication, or blood transfusions. Jaundice in newborns may be treated with bili lights. It is recommended that people be tested for G6PDD before certain medications, such as primaquine, are taken.About 400 million people have the condition globally. It is particularly common in certain parts of Africa, Asia, the Mediterranean, and the Middle East. Males are affected more often than females. In 2015 it is believed to have resulted in 33,000 deaths. Carriers of the G6PDD allele may be partially protected against malaria.

Glycerol-3-phosphate dehydrogenase

Glycerol-3-phosphate dehydrogenase (GPDH) is an enzyme that catalyzes the reversible redox conversion of dihydroxyacetone phosphate (a.k.a. glycerone phosphate, outdated) to sn-glycerol 3-phosphate.Glycerol-3-phosphate dehydrogenase serves as a major link between carbohydrate metabolism and lipid metabolism. It is also a major contributor of electrons to the electron transport chain in the mitochondria.

Older terms for glycerol-3-phosphate dehydrogenase include alpha glycerol-3-phosphate dehydrogenase (alphaGPDH) and glycerolphosphate dehydrogenase (GPDH). However, glycerol-3-phosphate dehydrogenase is not the same as glyceraldehyde 3-phosphate dehydrogenase (GAPDH), whose substrate is an aldehyde not an alcohol.


Glycolysis (from glycose, an older term for glucose + -lysis degradation) is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). Glycolysis is a sequence of ten enzyme-catalyzed reactions. Most monosaccharides, such as fructose and galactose, can be converted to one of these intermediates. The intermediates may also be directly useful. For example, the intermediate dihydroxyacetone phosphate (DHAP) is a source of the glycerol that combines with fatty acids to form fat.

Glycolysis is an oxygen-independent metabolic pathway. The wide occurrence of glycolysis indicates that it is an ancient metabolic pathway. Indeed, the reactions that constitute glycolysis and its parallel pathway, the pentose phosphate pathway, occur metal-catalyzed under the oxygen-free conditions of the Archean oceans, also in the absence of enzymes.In most organisms, glycolysis occurs in the cytosol. The most common type of glycolysis is the Embden–Meyerhof–Parnas (EMP pathway), which was discovered by Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. Glycolysis also refers to other pathways, such as the Entner–Doudoroff pathway and various heterofermentative and homofermentative pathways. However, the discussion here will be limited to the Embden–Meyerhof–Parnas pathway.The glycolysis pathway can be separated into two phases:

The Preparatory/Investment Phase – wherein ATP is consumed.

The Pay Off Phase – wherein ATP is produced.


In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the substrate gains a phosphate group and the high-energy ATP molecule donates a phosphate group. This transesterification produces a phosphorylated substrate and ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and ADP gains a phosphate group (producing a dephosphorylated substrate and the high energy molecule of ATP). These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis. Kinases are part of the larger family of phosphotransferases. Kinases should not be confused with phosphorylases, which catalyze the addition of inorganic phosphate groups to an acceptor, nor with phosphatases, which remove phosphate groups. The phosphorylation state of a molecule, whether it be a protein, lipid, or carbohydrate, can affect its activity, reactivity, and its ability to bind other molecules. Therefore, kinases are critical in metabolism, cell signalling, protein regulation, cellular transport, secretory processes, and many other cellular pathways, which makes them very important to human physiology.

Lithium iron phosphate battery

The lithium iron phosphate (LiFePO4) battery, also called LFP battery (with "LFP" standing for "lithium ferrophosphate"), is a type of rechargeable battery, specifically a lithium-ion battery, using LiFePO4 as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode. The specific capacity of LiFePO4 is higher than that of the related lithium cobalt oxide (LiCoO2) chemistry, but its energy density is less due to its lower operating voltage. The main drawback of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/C. Because of low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO4 is finding a number of roles in vehicle use, utility scale stationary applications, and backup power.

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP+ 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. It is used by all forms of cellular life.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. This extra phosphate is added by NAD+ kinase and removed by NADP+ phosphatase.


Nucleotides are organic molecules that serve as the monomer units for forming the nucleic acid polymers deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are the building blocks of nucleic acids; they are composed of three subunit molecules: a nitrogenous base (also known as nucleobase), a five-carbon sugar (ribose or deoxyribose), and at least one phosphate group.

A nucleoside is a nitrogenous base and a 5-carbon sugar. Thus a nucleoside plus a phosphate group yields a nucleotide.

Nucleotides also play a central role in metabolism at a fundamental, cellular level. They carry packets of chemical energy—in the form of the nucleoside triphosphates Adenosine triphosphate (ATP), Guanosine triphosphate (GTP), Cytidine triphosphate (CTP) and Uridine triphosphate (UTP)—throughout the cell to the many cellular functions that demand energy, which include: synthesizing amino acids, proteins and cell membranes and parts, moving the cell and moving cell parts (both internally and intercellularly), dividing the cell, etc. In addition, nucleotides participate in cell signaling (cyclic guanosine monophosphate or cGMP and cyclic adenosine monophosphate or cAMP), and are incorporated into important cofactors of enzymatic reactions (e.g. coenzyme A, FAD, FMN, NAD, and NADP+).

In experimental biochemistry, nucleotides can be radiolabeled with radionuclides to yield radionucleotides.

Pentose phosphate pathway

The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-phosphate, the last one a precursor for the synthesis of nucleotides. While it does involve oxidation of glucose, its primary role is anabolic rather than catabolic. The pathway is especially important in red blood cells (erythrocytes).

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. For most organisms, the pentose phosphate pathway takes place in the cytosol; in plants, most steps take place in plastid.Similar to glycolysis, the pentose phosphate pathway appears to have a very ancient evolutionary origin. The reactions of this pathway are mostly enzyme-catalyzed in modern cells, however, they also occur non-enzymatically under conditions that replicate those of the Archean ocean, and are catalyzed by metal ions, particularly ferrous ions (Fe(II)). This suggests that the origins of the pathway could date back to the prebiotic world.

Phosphoric acid

Phosphoric acid (also known as orthophosphoric acid or phosphoric(V) acid) is a weak acid with the chemical formula H3PO4. Orthophosphoric acid refers to phosphoric acid, which is the IUPAC name for this compound. The prefix ortho- is used to distinguish the acid from related phosphoric acids, called polyphosphoric acids. Orthophosphoric acid is a non-toxic acid, which, when pure, is a solid at room temperature and pressure. The conjugate base of phosphoric acid is the dihydrogen phosphate ion, H2PO−4, which in turn has a conjugate base of hydrogen phosphate, HPO2−4, which has a conjugate base of phosphate, PO3−4. Phosphates are essential for life.The most common source of phosphoric acid is an 85% aqueous solution; such solutions are colourless, odourless, and non-volatile. The 85% solution is a syrupy liquid, but still pourable. Although phosphoric acid does not meet the strict definition of a strong acid, the 85% solution is acidic enough to be corrosive.


Phosphorus is a chemical element with symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. It has a concentration in the Earth's crust of about one gram per kilogram (compare copper at about 0.06 grams). With few exceptions, minerals containing phosphorus are in the maximally oxidized state as inorganic phosphate rocks.

Elemental phosphorus was first isolated (as white phosphorus) in 1669 and emitted a faint glow when exposed to oxygen – hence the name, taken from Greek mythology, Φωσφόρος meaning "light-bearer" (Latin Lucifer), referring to the "Morning Star", the planet Venus. The term "phosphorescence", meaning glow after illumination, derives from this property of phosphorus, although the word has since been used for a different physical process that produces a glow. The glow of phosphorus is caused by oxidation of the white (but not red) phosphorus — a process now called chemiluminescence. Together with nitrogen, arsenic, antimony, and bismuth, phosphorus is classified as a pnictogen.

Phosphorus is essential for life. Phosphates (compounds containing the phosphate ion, PO43−) are a component of DNA, RNA, ATP, and phospholipids. Elemental phosphorus was first isolated from human urine, and bone ash was an important early phosphate source. Phosphate mines contain fossils because phosphate is present in the fossilized deposits of animal remains and excreta. Low phosphate levels are an important limit to growth in some aquatic systems. The vast majority of phosphorus compounds mined are consumed as fertilisers. Phosphate is needed to replace the phosphorus that plants remove from the soil, and its annual demand is rising nearly twice as fast as the growth of the human population. Other applications include organophosphorus compounds in detergents, pesticides, and nerve agents.

Pyridoxal phosphate

Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The Enzyme commission has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.

Ribose-phosphate diphosphokinase

Ribose-phosphate diphosphokinase (or phosphoribosyl pyrophosphate synthetase or ribose-phosphate pyrophosphokinase) is an enzyme that converts ribose 5-phosphate into phosphoribosyl pyrophosphate (PRPP). It is classified under EC

The enzyme is involved in the synthesis of nucleotides (purines and pyrimidines), cofactors NAD and NADP, and amino acids histidine and tryptophan, linking these biosynthetic processes to the pentose phosphate pathway, from which the substrate ribose 5-phosphate is derived. Ribose 5-phosphate is produced by the HMP Shunt Pathway from Glucose-6-Phosphate. The product phosphoribosyl pyrophosphate acts as an essential component of the purine salvage pathway and the de novo synthesis of purines. Dysfunction of the enzyme would thereby undermine purine metabolism. Ribose-phosphate pyrophosphokinase exists in bacteria, plants, and animals, and there are three isoforms of human ribose-phosphate pyrophosphokinase. In humans, the genes encoding the enzyme are located on the X chromosome.

Trisodium phosphate

Trisodium phosphate (TSP) is the inorganic compound with the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution. TSP is used as a cleaning agent, builder, lubricant, food additive, stain remover, and degreaser.The item of commerce is often partially hydrated and may range from anhydrous Na3PO4 to the dodecahydrate Na3PO4 • 12H2O. Most often found in white powder form, it can also be called trisodium orthophosphate or simply sodium phosphate.

UTP—glucose-1-phosphate uridylyltransferase

UTP—glucose-1-phosphate uridylyltransferase also known as glucose-1-phosphate uridylyltransferase (or UDP–glucose pyrophosphorylase) is an enzyme involved in carbohydrate metabolism. It synthesizes UDP-glucose from glucose-1-phosphate and UTP; i.e.,

glucose-1-phosphate + UTP UDP-glucose + pyrophosphate

UTP—glucose-1-phosphate uridylyltransferase is an enzyme found in all three domains (bacteria, eukarya, and archaea) as it is a key player in glycogenesis and cell wall synthesis. Its role in sugar metabolism has been studied extensively in plants in order to understand plant growth and increase agricultural production. Recently, human UTP—glucose-1-phosphate uridylyltransferase has been studied and crystallized, revealing a different type of regulation than other organisms previously studied. Its significance is derived from the many uses of UDP-glucose including galactose metabolism, glycogen synthesis, glycoprotein synthesis, and glycolipid synthesis.


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