Guanosine monophosphate

Guanosine monophosphate (GMP), also known as 5′-guanidylic acid or guanylic acid (conjugate base guanylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase guanine; hence it is a ribonucleoside monophosphate. Guanosine monophosphate is commercially produced by microbial fermentation.[1]

Not to be confused with Cyclic guanosine monophosphate.
Guanosine monophosphate
Space-filling model of guanosine monophosphate
Names
IUPAC name
5′-Guanylic acid
Systematic IUPAC name
[(2R,3S,4R,5R)-5-(2-Amino-6-oxo-1,6-dihydro-9H-purin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl dihydrogen phosphate
Other names
5′-Guanidylic acid,
E number E626
Identifiers
3D model (JSmol)
Abbreviations GMP
ChEMBL
ChemSpider
ECHA InfoCard 100.001.453
E number E626 (flavour enhancer)
MeSH Guanosine+monophosphate
UNII
  • C1=NC2=C(N1[C@H]3[C@@H]([C@@H]([C@H](O3)COP(=O)(O)O)O)O)NC(=NC2=O)N
Properties
C10H14N5O8P
Molar mass 363.223 g·mol−1
Acidity (pKa) 0.7, 2.4, 6.1, 9.4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

As an acyl substituent, it takes the form of the prefix guanylyl-.

De novo synthesis

GMP synthesis starts with D-ribose 5′-phosphate, a product of the pentose phosphate pathway. The synthesis proceeds by the gradual formation of the purine ring on carbon-1 of ribose, with CO2, glutamine, glycine, aspartate and one-carbon derivatives of tetrahydrofolate donating various elements towards the building of the ring[2]

As inhibitor of guanosine monophosphate synthesis in experimental models, the glutamine analogue DON can be used.[3]

cGMP

GMP can also exist as a cyclic structure known as cyclic GMP. Within certain cells the enzyme guanylyl cyclase makes cGMP from GTP.

cGMP plays an important role in mediating hormonal signaling.[2]

Sources

GMP was originally identified as the umami substance in dried shiitake mushroom. The drying process significantly increases GMP content with the breakdown of RNA. It can be found in a number of other mushrooms.[4]

Industrial production is based on fermentation: a bacterium converts sugars into AICA ribonucleotide, which is then converted chemically to GMP.[5] Tapioca starch is a possible sugar source.[6]

Food additive

Guanosine monophosphate is known as E number reference E626.[7] In the form of its salts, such as disodium guanylate (E627), dipotassium guanylate (E628) and calcium guanylate (E629), are food additives used as flavor enhancers to provide the umami taste.[7] It is often used in synergy with disodium inosinate; the combination is known as disodium 5′-ribonucleotides. Disodium guanylate is often found in instant noodles, potato chips and snacks, savoury rice, tinned vegetables, cured meats, and packet soup.

As it is a fairly expensive additive, it is usually not used independently of glutamic acid or monosodium glutamate (MSG), which also contribute umami. If inosinate and guanylate salts are present in a list of ingredients but MSG does not appear to be, the glutamic acid is likely provided as part of another ingredient, such as a processed soy protein complex (hydrolyzed soy protein), autolyzed yeast, or soy sauce.

See also

References
  1. "The Vegetarian Resource Group Blog". www.vrg.org. Retrieved 25 April 2018.
  2. Voet, Donald; Voet, Judith G. (2012). Biochemistry. USA: John Wiley & Sons Inc. pp. 1107–1109. ISBN 978-0-470-57095-1.
  3. Ahluwalia GS et al. Metabolism and action of amino acid analog anti-cancer agents ”, in Pharmac. Ther. (1990) 46: 243-271
  4. Kurihara, K (2015). "Umami the Fifth Basic Taste: History of Studies on Receptor Mechanisms and Role as a Food Flavor". BioMed Research International. 2015: 189402. doi:10.1155/2015/189402. PMC 4515277. PMID 26247011.
  5. Kinoshita, Kazumoto; Shiro, Teruo; Yamazaki, Akihiro; Kumashiro, Izumi; Takenishi, Tadao; Tsunoda, Toshinao (July 1967). "Industrial production of disodium 5?-guanylate". Biotechnology and Bioengineering. 9 (3): 329–342. doi:10.1002/bit.260090306. S2CID 84216811.
  6. Conn, Helen (1 February 1992). ""Umami": The Fifth Basic Taste". Nutrition & Food Science. 92 (2): 21–23. doi:10.1108/EUM0000000000953.
  7. "Additive categories | CEFF". www.ceff.info. Retrieved 2021-11-30.
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