serine

File:Betain-Serin.png

This compound is one of the proteinogenic amino acids. 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 by Emil Cramer.{{cite journal |last1=Cramer |first1=Emil |title=Ueber die Bestandtheile der Seide |journal=Journal für praktische Chemie |date=1865 |volume=96 |pages=76–98 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.hxgq72&view=1up&seq=94 |trans-title=On the constituents of silk |language=German}} Serine is named on p. 93: "Ich werde den in Frage stehenden Körper unter dem Namen Serin beschreiben." (I will describe the body [i.e., substance] in question by the name "serine".) Its name is derived from the Latin for silk, sericum. Serine's structure was established in 1902.{{cite journal |last1=Fischer |first1=Emil |last2=Leuchs |first2=Hermann |title=Synthese des Serins, der l-Glucosaminsäure und anderer Oxyaminosäuren |journal=Berichte der Deutschen Chemischen Gesellschaft |date=1902 |volume=35 |issue=3 |pages=3787–3805 |doi=10.1002/cber.190203503213 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.cl1i27&view=1up&seq=1255 |trans-title=Synthesis of serine, of l-glucosaminic acid, and other oxyamino acids |language=de|url-access=subscription }}{{cite encyclopedia|title=Serine|url=http://www.encyclopedia.com/topic/serine.aspx|encyclopedia=The Columbia Encyclopedia 6th ed.|publisher=encyclopedia.com|access-date=22 October 2012}}

The biosynthesis of serine starts with the oxidation of 3-phosphoglycerate (an intermediate from glycolysis) to 3-phosphohydroxypyruvate and NADH by phosphoglycerate dehydrogenase ({{EC number|1.1.1.95}}). Reductive amination (transamination) of this ketone by phosphoserine transaminase ({{EC number|2.6.1.52}}) yields 3-phosphoserine (O-phosphoserine) which is hydrolyzed to serine by phosphoserine phosphatase ({{EC number|3.1.3.3}}).{{cite book | last1 = Stryer | first1 = Lubert | title = Biochemistry | date = 1988 | publisher = W.H. Freeman | location = New York | isbn = 978-0-7167-1843-7 | edition = 3rd | page = [https://archive.org/details/biochemistry3rdedi00stry/page/580 580] | url-access = registration | url = https://archive.org/details/biochemistry3rdedi00stry/page/580 }}KEGG [http://www.genome.jp/dbget-bin/www_bget?ec:3.1.3.3 EC 3.1.3.3] etc.

In bacteria such as E. coli these enzymes are encoded by the genes serA (EC 1.1.1.95), serC (EC 2.6.1.52), and serB (EC 3.1.3.3).Uniprot: [https://www.uniprot.org/uniprot/P0AGB0 serB]

File:Serine biosynthesis.svg

Serine hydroxymethyltransferase (SMHT) also catalyzes the biosynthesis of glycine (retro-aldol cleavage) from serine, transferring the resulting formalddehyde synthon to 5,6,7,8-tetrahydrofolate. However, that reaction is reversible, and will convert excess glycine to serine.{{cite book | first1 = Albert L. | last1 = Lehninger | first2 = David L. | last2 = Nelson | first3 = Michael M. | last3 = Cox | title = Principles of Biochemistry | edition = 3rd | publisher = W. H. Freeman | location = New York | year = 2000 | isbn = 1-57259-153-6 | url-access = registration | url = https://archive.org/details/lehningerprincip01lehn }} SHMT is a pyridoxal phosphate (PLP) dependent enzyme.

Industrially, L-serine is produced from glycine and methanol catalyzed by hydroxymethyltransferase.{{Ullmann|author=Karlheinz Drauz, Ian Grayson, Axel Kleemann, Hans-Peter Krimmer, Wolfgang Leuchtenberger, Christoph Weckbecker|year=2006|doi=10.1002/14356007.a02_057.pub2}}

Racemic serine can be prepared in the laboratory from methyl acrylate in several steps:{{cite journal | journal = Org. Synth. | last1 = Carter | first1 = Herbert E. | author-link1 = H. E. Carter | last2 = West | first2 = Harold D. | author-link2 = Harold Dadford West | title = dl-Serine | url = http://www.orgsyn.org/demo.aspx?prep=cv3p0774 | volume = 20 | pages = 81 | year = 1940 | doi=10.15227/orgsyn.020.0081| url-access = subscription }}

:File:Synthesis of dl-serine.svg

Hydrogenation of serine gives the diol serinol:

:{{chem2|HOCH2CH(NH2)CO2H + 2 H2 → HOCH2CH(NH2)CH2OH + 2 H2O}}

File:Cysteine biosynthesis.svg 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, as well as tryptophan in bacteria. It is also the precursor to numerous other metabolites, including sphingolipids and folate, which is the principal donor of one-carbon fragments in biosynthesis.{{Citation needed|date=January 2021}}

D-Serine, synthesized in neurons by serine racemase from L-serine (its enantiomer), serves as a neuromodulator by coactivating NMDA receptors, making them able to open if they then also bind glutamate. D-serine is a potent agonist at the glycine site (NR1) of canonical diheteromeric NMDA receptors. For the receptor to open, glutamate and either glycine or D-serine must bind to it; in addition a pore blocker must not be bound (e.g. Mg²⁺ or Zn²⁺).{{cite journal |vauthors=Liu Y, Hill RH, Arhem P, von Euler G |title=NMDA and glycine regulate the affinity of the Mg2+-block site in NR1-1a/NR2A NMDA receptor channels expressed in Xenopus oocytes |journal=Life Sciences |volume=68 |issue=16 |pages=1817–1826 |year=2001 |pmid=11292060 |doi=10.1016/S0024-3205(01)00975-4 }} Some research has shown that D-serine is a more potent agonist at the NMDAR glycine site than glycine itself.{{cite journal | last1=MacKay | first1=Mary-Anne B. | last2=Kravtsenyuk | first2=Maryana | last3=Thomas | first3=Rejish | last4=Mitchell | first4=Nicholas D. | last5=Dursun | first5=Serdar M. | last6=Baker | first6=Glen B. | title=D-Serine: Potential Therapeutic Agent and/or Biomarker in Schizophrenia and Depression? | journal=Frontiers in Psychiatry | date=6 February 2019 | volume=10 | page=25 | issn=1664-0640 | doi=10.3389/fpsyt.2019.00025 | pmid=30787885 | pmc=6372501 | quote=D-Serine is more potent than glycine as a coagonist at the NMDA receptor, has a regional distribution in the brain that is similar to that of NMDA receptors and appears to be more closely associated with synaptic NMDA receptors than glycine (which is more closely associated with non-synaptic NMDA receptors).| doi-access=free }}{{cite journal | last1=Wolosker | first1=Herman | last2=Balu | first2=Darrick T. | title=D-Serine as the gatekeeper of NMDA receptor activity: implications for the pharmacologic management of anxiety disorders | journal=Translational Psychiatry | volume=10 | issue=1 | date=9 June 2020 | page=184 | issn=2158-3188 | doi=10.1038/s41398-020-00870-x | pmid=32518273 | pmc=7283225 | quote=D-Serine is functionally a more potent activator of synaptic NMDARs than glycine, and mounting evidence suggests that it serves as the major NMDAR co-agonist in limbic brain regions implicated in neuropsychiatric disorders.}} However, D-serine has been shown to work as an antagonist/inverse co-agonist of t-NMDA receptors through the glycine binding site on the GluN3 subunit.{{cite journal |last1=Pilli |first1=J. |last2=Kumar |first2=S. S. |date=2012-10-11 |title=Triheteromeric N-methyl-D-aspartate receptors differentiate synaptic inputs onto pyramidal neurons in somatosensory cortex: involvement of the GluN3A subunit |url=https://pubmed.ncbi.nlm.nih.gov/22814002 |journal=Neuroscience |volume=222 |pages=75–88 |doi=10.1016/j.neuroscience.2012.07.020 |issn=1873-7544 |pmid=22814002|s2cid=23158971 }}{{cite journal |last1=Beesley |first1=Stephen |last2=Kumar |first2=Sanjay S. |date=2023-11-01 |title=The t-N-methyl-d-aspartate receptor: Making the case for d-Serine to be considered its inverse co-agonist |journal=Neuropharmacology |volume=238 |pages=109654 |doi=10.1016/j.neuropharm.2023.109654 |issn=1873-7064 |pmid=37437688|doi-access=free }}

D-serine was thought to exist only in bacteria until relatively recently; it was the second D amino acid discovered to naturally exist in humans, present as a signaling molecule in the brain, soon after the discovery of D-aspartate. Had D amino acids been discovered in humans sooner, the glycine site on the NMDA receptor might instead be named the D-serine site.{{cite journal | vauthors = Mothet JP, Parent AT, Wolosker H, Brady RO, Linden DJ, Ferris CD, Rogawski MA, Snyder SH | title = D-Serine is an endogenous ligand for the glycine site of the N-methyl-D-aspartate receptor | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 97 | issue = 9 | pages = 4926–4931 | date = Apr 2000 | pmid = 10781100 | pmc = 18334 | doi = 10.1073/pnas.97.9.4926 | bibcode = 2000PNAS...97.4926M | doi-access = free }} Apart from central nervous system, D-serine plays a signaling role in peripheral tissues and organs such as cartilage,{{cite journal | vauthors = Takarada T, Hinoi E, Takahata Y, Yoneda Y | title = Serine racemase suppresses chondrogenic differentiation in cartilage in a Sox9-dependent manner | journal = Journal of Cellular Physiology | volume = 215 | issue = 2 | pages = 320–328 | date = May 2008 | pmid = 17929246 | doi = 10.1002/jcp.21310 | s2cid = 45669104 }} kidney,{{cite journal | vauthors = Ma MC, Huang HS, Chen YS, Lee SH | title = Mechanosensitive N-methyl-D-aspartate receptors contribute to sensory activation in the rat renal pelvis | journal = Hypertension | volume = 52 | issue = 5 | pages = 938–944 | date = Nov 2008 | pmid = 18809793 | doi = 10.1161/HYPERTENSIONAHA.108.114116 | doi-access = free }} and corpus cavernosum.{{cite journal | vauthors = Ghasemi M, Rezania F, Lewin J, Moore KP, Mani AR | title = D-Serine modulates neurogenic relaxation in rat corpus cavernosum | journal = Biochemical Pharmacology | volume = 79 | issue = 12 | pages = 1791–1796 | date = Jun 2010 | pmid = 20170643 | doi = 10.1016/j.bcp.2010.02.007 }}

Pure D-serine is an off-white crystalline powder with a very faint musty aroma. D-Serine is sweet with an additional minor sour taste at medium and high concentrations.{{cite journal | vauthors = Kawai M, Sekine-Hayakawa Y, Okiyama A, Ninomiya Y | title = Gustatory sensation of L- and D-amino acids in humans | journal = Amino Acids | volume = 43 | issue = 6 | pages = 2349–2358 | date = Dec 2012 | pmid = 22588481 | doi = 10.1007/s00726-012-1315-x | s2cid = 17671611 }}

Serine deficiency disorders are rare defects in the biosynthesis of the amino acid L-serine. At present three disorders have been reported:

• 3-phosphoglycerate dehydrogenase deficiency
• 3-phosphoserine phosphatase deficiency
• Phosphoserine aminotransferase deficiency

These enzyme defects lead to severe neurological symptoms such as congenital microcephaly and severe psychomotor retardation and in addition, in patients with 3-phosphoglycerate dehydrogenase deficiency to intractable seizures. These symptoms respond to a variable degree to treatment with L-serine, sometimes combined with glycine.{{cite journal| author = de Koning TJ| title = Treatment with amino acids in serine deficiency disorders | journal= Journal of Inherited Metabolic Disease| volume = 29| issue = 2| pages = 347–351|date=April 2006|pmid = 16763900| doi=10.1007/s10545-006-0269-0| s2cid = 25013468 }}{{cite journal|author1=Tabatabaie L |author2=Klomp LW |author3=Berger R |author4=de Koning TJ | title = L-Serine synthesis in the central nervous system: a review on serine deficiency disorders| journal = Mol Genet Metab| volume = 99| issue = 3| pages = 256–262|date=March 2010| doi= 10.1016/j.ymgme.2009.10.012| pmid = 19963421}}

Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, as well as for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD).{{cite web|title=Patient registry|url=http://intd-online.org/}}

Besides disruption of serine biosynthesis, its transport may also become disrupted. One example is spastic tetraplegia, thin corpus callosum, and progressive microcephaly, a disease caused by mutations that affect the function of the neutral amino acid transporter A.

The classification of L-serine as a non-essential amino acid has come to be considered as conditional, since vertebrates such as humans cannot always synthesize optimal quantities over entire lifespans.{{cite journal|last1=Metcalf|first1=J. S.|last2=Dunlop|first2=R. A.|last3=Powell|first3=J. T.|last4=Banack|first4=S. A.|last5=Cox|first5=P. A.|title=L-Serine: a Naturally-Occurring Amino Acid with Therapeutic Potential|journal=Neurotoxicity Research|volume=33|issue=1|year=2017|pages=213–221|issn=1029-8428|doi=10.1007/s12640-017-9814-x|pmid=28929385|s2cid=20271849}} Safety of L-serine has been demonstrated in an FDA-approved human phase I clinical trial with Amyotrophic Lateral Sclerosis, ALS, patients (ClinicalTrials.gov identifier: NCT01835782),{{cite journal | vauthors = Dunlop RA, Cox PA, Banack SA, Rodgers KJ | title = The non-protein amino acid BMAA is misincorporated into human proteins in place of L-serine causing protein misfolding and aggregation | journal = PLOS ONE | year = 2013 | volume = 8 | issue = 9 | pages = e75376 | pmid = 24086518 | pmc = 3783393 | doi = 10.1371/journal.pone.0075376 | bibcode = 2013PLoSO...875376D | doi-access = free }}{{cite journal|last1=Levine|first1=Todd D.|last2=Miller|first2=Robert G.|last3=Bradley|first3=Walter G.|last4=Moore|first4=Dan H.|last5=Saperstein|first5=David S.|last6=Flynn|first6=Lynne E.|last7=Katz|first7=Jonathan S.|last8=Forshew|first8=Dallas A.|last9=Metcalf|first9=James S.|last10=Banack|first10=Sandra A.|last11=Cox|first11=Paul A.|date=2017-01-02|title=Phase I clinical trial of safety of L-serine for ALS patients|journal=Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration|language=en|volume=18|issue=1–2|pages=107–111|doi=10.1080/21678421.2016.1221971|pmid=27589995|s2cid=4584977|issn=2167-8421|doi-access=free}} but treatment of ALS symptoms has yet to be shown. A 2011 meta-analysis found adjunctive sarcosine to have a medium effect size for negative and total symptoms of schizophrenia.{{cite journal | vauthors = Singh SP, Singh V | title = Meta-analysis of the efficacy of adjunctive NMDA receptor modulators in chronic schizophrenia | journal = CNS Drugs | volume = 25 | issue = 10 | pages = 859–885 | date = Oct 2011 | pmid = 21936588 | doi = 10.2165/11586650-000000000-00000 | s2cid = 207299820 }} There also is evidence that L‐serine could acquire a therapeutic role in diabetes.{{cite journal|last1=Holm|first1=Laurits J.|last2=Buschard|first2=Karsten|title=L-serine: a neglected amino acid with a potential therapeutic role in diabetes|journal=APMIS|year=2019|volume=127|issue=10|pages=655–659|issn=0903-4641|doi=10.1111/apm.12987|pmid=31344283|pmc=6851881|doi-access=free}}

D-Serine is being studied in rodents as a potential treatment for schizophrenia.{{cite journal | vauthors = Balu DT, Li Y, Puhl MD, Benneyworth MA, Basu AC, Takagi S, Bolshakov VY, Coyle JT | title = Multiple risk pathways for schizophrenia converge in serine racemase knockout mice, a mouse model of NMDA receptor hypofunction | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 26 | pages = E2400–E2409 | date = Jun 2013 | pmid = 23729812 | doi = 10.1073/pnas.1304308110 | pmc=3696825| bibcode = 2013PNAS..110E2400B | doi-access = free }} D-Serine also has been described as a potential biomarker for early Alzheimer's disease (AD) diagnosis, due to a relatively high concentration of it in the cerebrospinal fluid of probable AD patients.{{cite journal | vauthors = Madeira C, Lourenco MV, Vargas-Lopes C, Suemoto CK, Brandão CO, Reis T, Leite RE, Laks J, Jacob-Filho W, Pasqualucci CA, Grinberg LT, Ferreira ST, Panizzutti R | title = D-Serine levels in Alzheimer's disease: implications for novel biomarker development | journal = Translational Psychiatry | volume = 5 | issue = 5 | pages = e561 | date = May 5, 2015 | pmid = 25942042 | doi = 10.1038/tp.2015.52 | pmc=4471283}} D-serine, which is made in the brain, has been shown to work as an antagonist/inverse co-agonist of t-NMDA receptors mitigating neuron loss in an animal model of temporal lobe epilepsy.{{cite journal |last1=Beesley |first1=Stephen |last2=Sullenberger |first2=Thomas |last3=Crotty |first3=Kathryn |last4=Ailani |first4=Roshan |last5=D'Orio |first5=Cameron |last6=Evans |first6=Kimberly |last7=Ogunkunle |first7=Emmanuel O. |last8=Roper |first8=Michael G. |last9=Kumar |first9=Sanjay S. |date=2020-10-02 |title=D-serine mitigates cell loss associated with temporal lobe epilepsy |journal=Nature Communications |volume=11 |issue=1 |pages=4966 |doi=10.1038/s41467-020-18757-2 |issn=2041-1723 |pmc=7532172 |pmid=33009404|bibcode=2020NatCo..11.4966B }}

D-Serine has been theorized as a potential treatment for sensorineural hearing disorders such as hearing loss and tinnitus.{{cite journal | last1=Wang | first1=Jing | last2=Serratrice | first2=Nicolas | last3=Lee | first3=Cindy J. | last4=François | first4=Florence | last5=Sweedler | first5=Jonathan V. | last6=Puel | first6=Jean-Luc | last7=Mothet | first7=Jean-Pierre | last8=Ruel | first8=Jérôme | title=Physiopathological Relevance of D-Serine in the Mammalian Cochlea | journal=Frontiers in Cellular Neuroscience | publisher=Frontiers Media SA | volume=15 | date=17 December 2021 | page=733004 | issn=1662-5102 | doi=10.3389/fncel.2021.733004| pmid=34975405 | pmc=8718999 | doi-access=free }}

• Isoserine
• Homoserine (isothreonine)
• Serine octamer cluster

{{reflist|33em}}

• [http://gmd.mpimp-golm.mpg.de/Spectrums/5aef15ff-bca8-4625-9dc1-a1c891cf43a7.aspx Serine MS Spectrum]

{{Amino acids}}

{{Amino acid metabolism intermediates}}

{{Neurotransmitters}}

{{Ionotropic glutamate receptor modulators}}

{{Glycine receptor modulators}}

{{Lysophospholipid signaling}}

Category:Alpha-Amino acids

Category:Proteinogenic amino acids

Category:Glucogenic amino acids

Category:NMDA receptor agonists

Category:Glycine receptor agonists

Category:Aldols

Category:Amino alcohols

Category:Inhibitory amino acids