AskDefine | Define serine

Dictionary Definition

serine n : a sweetish crystalline amino acid involved in the synthesis by the body of cysteine

User Contributed Dictionary



  1. A nonessential amino acid, CH2OH.CH(NH2)COOH, found in most animal proteins, especially silk.

Derived terms


nonessential amino acid; CH2OH.CH(NH2)COOH
  • Spanish: serina

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Extensive Definition

Serine (abbreviated as Ser or S) is an organic compound with the formula HO2CCH(NH2)CH2OH. It is one of the 20 naturally occurring proteinogenic amino acids. Its codons are UCU, UCC, UCA, UCG, AGU and AGC. Only the L-stereoisomer appears naturally in proteins. It is not essential to the human diet, since it is synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865. Its name is derived from the Latin for silk, sericum. Serine's structure was established in 1902. The hydroxyl group attached makes it a polar amino acid.


The synthesis of serine starts with the oxidation of 3-phosphoglycerate forming 3-phosphohydroxypyruvate and NADH. Reductive amination of this ketone followed by hydrolysis affords serine. Serine hydroxymethyltransferase catalyzes the reversible, simultaneous conversions of L-serine to glycine (retro-aldol cleavage) and 5,6,7,8-tetrahydrofolate to 5,10-methylenetetrahydrofolate (hydrolysis).



Serine is important in metabolism in that it participates in the biosynthesis of purines and pyrimidines. It is also the precursor to several amino acids, including glycine, cysteine, tryptophan (in bacteria). It is also the precursor to numerous of other metabolites, including sphingolipids. Serine is also a precursor to folate, which is the principal donor of one carbon fragments in biosynthesis.


Serine plays an important role in the catalytic function of many enzymes. It has been shown to occur in the active sites of chymotrypsin, trypsin, and many other enzymes. The so-called nerve gases and many substances used in insecticides have been shown to act by combining with a residue of serine in the active site of acetylcholine esterase, inhibiting the enzyme completely. The unmetabolized acetylcholine cannot be recycled into the nerve for signaling. This results in depletion of acetylcholine at the neuromuscular junction, resulting in the inability to control muscles, which results in asphyxiation, and death.
As a constituent (residue) of proteins, its side chain can undergo O-linked glycosylation. This might be important in explaining some of the devastating consequences of diabetes. It is one of three amino acid residues that are commonly phosphorylated by kinases during cell signaling in eukaryotes. Phosphorylated serine residues are often referred to as phosphoserine. Serine proteases are a common type of protease.


D-serine, synthesized by serine racemase from L-serine, serves as a neuronal signaling molecule by activating NMDA receptors in the brain.

Chemical Synthesis

Serine is prepared from methyl acrylate.

See also


serine in Arabic: سيرين
serine in Catalan: Serina
serine in Czech: Serin
serine in Danish: Serin
serine in German: Serin
serine in Estonian: Seriin
serine in Spanish: Serina
serine in Esperanto: Serino
serine in French: Sérine
serine in Korean: 세린
serine in Croatian: Serin
serine in Indonesian: Serin
serine in Italian: Serina (chimica)
serine in Hebrew: סרין
serine in Latvian: Serīns
serine in Luxembourgish: Serin
serine in Lithuanian: Serinas
serine in Hungarian: Szerin
serine in Dutch: Serine
serine in Japanese: セリン
serine in Norwegian: Serin
serine in Polish: Seryna
serine in Portuguese: Serina
serine in Russian: Серин
serine in Finnish: Seriini
serine in Swedish: Serin
serine in Tamil: செர்ரீன்
serine in Turkish: Serin
serine in Ukrainian: Серин
serine in Chinese: 絲氨酸
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