Sugar phosphates (

sugars Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...

that have added or substituted

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

groups) are often used in biological systems to store or transfer

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of hea ...

. They also form the backbone for DNA and RNA. Sugar phosphate backbone geometry is altered in the vicinity of the modified nucleotides. Examples include: * Dihydroxyacetonephosphate *

Glucose-6-phosphate Glucose 6-phosphate (G6P, sometimes called the Robison ester) is a glucose sugar phosphorylated at the hydroxy group on carbon 6. This dianion is very common in cells as the majority of glucose entering a cell will become phosphorylated in this wa ...

* Phytic acid *

Teichoic acid Teichoic acids (''cf.'' Greek τεῖχος, ''teīkhos'', "wall", to be specific a fortification wall, as opposed to τοῖχος, ''toīkhos'', a regular wall) are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohydr ...

Electronic structure of the sugar-phosphate backbone

The sugar-phosphate backbone has

multiplex Multiplex may refer to: * Multiplex (automobile), a former American car make * Multiplex (comics), a DC comic book supervillain * Multiplex (company), a global contracting and development company * Multiplex (assay), a biological assay which measu ...

electronic structure and the electron

delocalisation In chemistry, delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond.IUPAC Gold Boo''delocalization''/ref> The term delocalization is general and can have slightly di ...

complicates its

theoretical A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...

description. Some part of the electronic density is delocalised over the whole backbone and the extent of the delocalisation is affected by backbone conformation due to hyper-conjugation effects. Hyper-conjugation arises from donor-acceptor interactions of localised orbitals in 1,3 positions.

Phosphodiesters in DNA and RNA

The phosphodiester backbone of DNA and RNA consists of pairs of

deoxyribose Deoxyribose, or more precisely 2-deoxyribose, is a monosaccharide with idealized formula H−(C=O)−(CH2)−(CHOH)3−H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of a hydroxy group. D ...

ribose Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−(C=O)−(CHOH)4−H. The naturally-occurring form, , is a component of the ribonucleotides from which RNA is built, and so this compo ...

sugars linked by phosphates at the respective 3' and 5' positions. The backbone is negatively charged and

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are ...

, which allows strong interactions with water. Sugar-phosphate backbone forms the structural framework of

nucleic acids Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...

, including DNA and RNA. Sugar phosphates are defined as carbohydrates to which a phosphate group is bound by an ester or an either linkage, depending on whether it involves an alcoholic or a hemiacetalic hydroxyl, respectively.

Solubility In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

, acid

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

rates, acid strengths, and ability to act as sugar group donors are the knowledge of physical and chemical properties required for the analysis of both types of sugar phosphates. The photosynthetic carbon reduction cycle is closely associated with sugar phosphates, and sugar phosphates are one of the key molecules in metabolism,(Sugar phosphates are major players in

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

due to their task of storing and transferring energy. Not only ribose 5-phosphate but also fructose 6-phosphate are an intermediate of the pentose-phosphate pathway which generates

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 NAD ...

(NADPH) and pentoses from glucose polymers and their

degradation Degradation may refer to: Science * Degradation (geology), lowering of a fluvial surface by erosion * Degradation (telecommunications), of an electronic signal * Biodegradation of organic substances by living organisms * Environmental degradatio ...

products.) oxidative pentose phosphate pathways, gluconeogenesis, important intermediates in glycolysis. Sugar phosphates are not only involved in metabolic regulation and signaling but also involved in the synthesis of other phosphate compounds.

Peptide nucleic acids

Peptide nucleic acid (PNA) is a nucleic acid in which natural nucleic acid has been replaced by a

synthetic peptide In organic chemistry, peptide synthesis is the production of peptides, compounds where multiple amino acids are linked via amide bonds, also known as peptide bonds. Peptides are chemically synthesized by the condensation reaction of the carboxyl ...

backbone formed from ''N''-(2-amino-ethyl)-glycine units along with sugar phosphate backbone forming in an achiral and uncharged moiety that mimics RNA or DNA

oligonucleotide Oligonucleotides are short DNA or RNA molecules, oligomers, that have a wide range of applications in genetic testing, research, and forensics. Commonly made in the laboratory by solid-phase chemical synthesis, these small bits of nucleic acids ...

s. PNA cannot be degraded inside living cells but it is chemically stable and resistant to

hydrolytic Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysi ...

(enzymatic) cleavage.

Role in metabolism

Sugar phosphates are major players in

due to their task of storing and transferring energy. Not only ribose 5-phosphate but also fructose 6-phosphate are an intermediate of the pentose-phosphate pathway which generates

(NADPH) and pentoses from glucose polymers and their

products. The pathway is known as glycolysis where the same carbohydrates are degraded into pyruvates thus providing energy. Enzymes are catalysed for the reactions of these pathways. Some enzymes contain metal centers in their active site which is important part of the enzymes and as well as for the catalysed reaction. The phosphate group can coordinate to the metal center for example, 1,6-bisphosphatase and ADP-ribose pyrophosphatase. Phosphoglycerate and several sugar phosphates that are known intermediates of the Calvin photosynthetic

carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major componen ...

, stimulate light-dependent carbon dioxide fixation by isolated chloroplasts. This ability is shared by certain other metabolites (e.g. glucose 1-phosphate) from which the accepted Calvin-cycle intermediates could easily be derived by known metabolic routes.

References

External links

* {{MeshName, Sugar+Phosphates Sugar Phosphates Nucleotides DNA RNA