Serine: Wikis

  

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Serine
Serin - Serine.svg
IUPAC name
Other names 2-Amino-3-hydroxypropionic acid
Identifiers
CAS number 302-84-1 Yes check.svgY,
56-45-1 (L-isomer)
312-84-5 (D-isomer)
PubChem 617
EC-number 206-130-6
SMILES
InChI
ChemSpider ID 597
Properties[1]
Molecular formula C3H7NO3
Molar mass 105.09 g mol−1
Appearance white crystals or powder
Density 1.603 g/cm3 (22 ºC)
Melting point

246 ºC decomp.

Solubility in water soluble
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Serine (abbreviated as Ser or S)[2] is an organic compound with the formula HO2CCH(NH2)CH2OH.

Contents

Occurrence

It is one of the 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. By virtue of the hydroxyl group, serine is classified as a polar amino acid.

Skeletal formula of L-serine
Stick model of L-serine.
Two representations of the structure of L-serine.

Betaines

(S)-Serine (left) and (R)-serine (right) in zwitterionic form at neutral pH

Biosynthesis

The biosynthesis of serine starts with the oxidation of 3-phosphoglycerate to 3-phosphohydroxypyruvate and NADH. Reductive amination of this ketone followed by hydrolysis gives 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).[3]

Chemical synthesis

Racemic serine can be prepared from methyl acrylate via several steps.[4] It is also naturally produced when UV light illuminates simple ices such as a combination of water, methanol, hydrogen cyanide, and ammonia, suggesting that it may be easily produced in cold regions of space. [5]

Function

Metabolic

Cysteine synthesis from serine. Cystathionine beta synthase catalyzes the upper reaction and cystathionine gamma-lyase catalyzes the lower reaction.

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

Structural role

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, which may be functionally related to 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.

Signaling

D-Serine, synthesized by serine racemase from L-serine, serves as a neuronal signal by activating NMDA receptors in the brain.[6]

See also

References

  1. ^ Weast, Robert C., ed. (1981), CRC Handbook of Chemistry and Physics (62nd ed.), Boca Raton, FL: CRC Press, p. C-512, ISBN 0-8493-0462-8  .
  2. ^ "Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)", Pure Appl. Chem. 56 (5): 595–624, 1984, doi:10.1351/pac198456050595  .
  3. ^ Lehninger, Albert L.; Nelson, David L.; Cox, Michael M. (2000), Principles of Biochemistry (3rd ed.), New York: W. H. Freeman, ISBN 1-57259-153-6  .
  4. ^ Carter, Herbert E.; West, Harold D. (1940), "dl-Serine", Org. Synth. 20: 81, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0774  ; Coll. Vol. 3: 774  .
  5. ^ Elsila, Jamie E.; Dworkin, Jason P.; Bernstein, Max P.; Martin, Mildred P.; Sandford, Scott A. (2007), "Mechanisms of Amino Acid Formation in Interstellar Ice Analogs", Astrophys. J. 660 (1): 911–18, doi:10.1086/513141  .
  6. ^ Mothet, Jean-Pierre; Parent, Angèle T.; Wolosker, Herman; Brady, Roscoe O., Jr.; Linden, David J.; Ferris, Christopher D.; Rogawski, Michael A.; Snyder, Solomon H. (2000), "d-Serine is an endogenous ligand for the glycine site of the N-methyl-d-aspartate receptor", Proc. Natl. Acad. Sci. USA 97 (9): 4926–31, doi:10.1073/pnas.97.9.4926, PMID 10781100, PMC 18334, http://www.pnas.org/cgi/pmidlookup?view=long&pmid=10781100  .

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