関: methionine enkephalin

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the 13th letter of the Roman alphabet (同)m
an endorphin having opiate qualities that occurs in the brain and spinal cord and elsewhere

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/09/06 12:17:23」(JST)

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Met-enkephalin, also known as metenkefalin (INN), sometimes referred to as opioid growth factor (OGF),^[1] is a naturally occurring, endogenous opioid peptide that has opioid effects of a relatively short duration. It is one of the two forms of enkephalin, the other being leu-enkephalin. The enkephalins are considered to be the primary endogenous ligands of the δ-opioid receptor, due to their high potency and selectivity for the site over the other endogenous opioids.^[2]

History

Met-enkephalin was discovered and characterized by Hughes, Kosterlitz, et al. in 1975 after a search for endogenous ligands of the opioid receptors.^[3]

Chemistry

Met-enkephalin is a pentapeptide with the amino acid sequence tyr-gly-gly-phe-met. The tyrosine residue at position 1 is thought to be analogous to the 3-hydroxyl group on morphine.^{[citation needed]}

Pharmacology

Distribution

Met-enkephalin is found mainly in the adrenal medulla and throughout the central nervous system (CNS), including in the striatum, cerebral cortex, olfactory tubercle, hippocampus, septum, thalamus, and periaqueductal gray, as well as the dorsal horn of the spinal cord.^[2] It is also present in the periphery, notably in some primary afferent fibers that innervate the pelvic viscera.^[2]

Biosynthesis

Met-enkephalin is synthesized from proenkephalin via proteolyic cleavage^[4] in two metabolic steps. Proenkephalin A is first reduced by either one of two trypsin-like endopeptidase enzymes, prohormone convertase 1 (PC1) or prohormone convertase 2 (PC2); then, the resulting intermediates are further reduced by the enzyme carboxypeptidase E (CPE; previously known as enkephalin convertase (EC)).^[5]^[6] Proenkephalin A contains four sequences of met-enkephalin (at the following positions: 100–104; 107–111; 136–140; 210–214), and as a result, its cleavage generates four copies of met-enkephalin peptides at once.^[4] In addition, anabolism of proenkephalin A results in the production of one copy each of two C-terminal-extended met-enkephalin derivatives, the heptapeptide met-enkephalin-arg-phe (261–267), and the octapeptide met-enkephalin-arg-gly-leu (186–193),^[4] though whether they affect the opioid receptors in a similar manner as met-enkephalin is not entirely clear.^[7]

Clearance

Met- and leu-enkephalin are metabolized by a variety of different enzymes, including aminopeptidase N (APN),^[8] neutral endopeptidase (NEP),^[8] dipeptidyl peptidase 3 (DPP3),^[8] carboxypeptidase A6 (CPA6),^[9] and angiotensin-converting enzyme (ACE).^[10] These enzymes are sometimes referred to as enkephalinases.

Pharmacodynamics

Met-enkephalin is a potent agonist of the δ-opioid receptor, and to a lesser extent the μ-opioid receptor, with little to no effect on the κ-opioid receptor. It is through these receptors that met-enkephalin produces its opioid effects, such as analgesia and antidepressant-like effects.

It is also the endogenous ligand of the opioid growth factor receptor (OGFR; formerly known as the ζ-opioid receptor), which plays a role in the regulation of tissue growth and regeneration; hence why met-enkephalin is sometimes called OGF instead.

Pharmacokinetics

Met-enkephalin has low bioavailability, is rapidly metabolized, and has a very short half-life (minutes).^[3]^[11] These properties are considered undesirable in pharmaceuticals as large doses would need to be administered multiple times an hour to maintain a therapeutically relevant effect, making it unlikely that met-enkephalin will ever be used as a medicine.

References

^ Zagon IS, Isayama T, McLaughlin PJ (January 1994). "Preproenkephalin mRNA expression in the developing and adult rat brain". Brain Research. Molecular Brain Research. 21 (1-2): 85–98. doi:10.1016/0169-328x(94)90381-6. PMID 8164525.
^ ^a ^b ^c Christoph Stein (1999). = 4Rfr8cQayvgC&pg = PA22 Opioids in pain control: basic and clinical aspects Check |url= value (help). Cambridge University Press. pp. 22–23. ISBN 978-0-521-62269-1. Retrieved 25 November 2011.
^ ^a ^b Thomas Carleton Moore (1993). = dJyJGevjkzQC&pg = PA179 Neurovascular immunology: vasoactive neurotransmitters and modulators in cellular immunity and memory Check |url= value (help). CRC Press. p. 179. ISBN 978-0-8493-6894-3. Retrieved 25 November 2011.
^ ^a ^b ^c Fleur L. Strand (1999). = PNPU0sknfCUC&pg = PA348 Neuropeptides: regulators of physiological processes Check |url= value (help). MIT Press. p. 348. ISBN 978-0-262-19407-5. Retrieved 25 November 2011.
^ Costa E, Mocchetti I, Supattapone S, Snyder SH (July 1987). "Opioid peptide biosynthesis: enzymatic selectivity and regulatory mechanisms". The FASEB Journal. 1 (1): 16–21. PMID 3111927.
^ Krajnik M, Schäfer M, Sobanski P, et al. (May 2010). "Enkephalin, its precursor, processing enzymes, and receptor as part of a local opioid network throughout the respiratory system of lung cancer patients". Human Pathology. 41 (5): 632–42. doi:10.1016/j.humpath.2009.08.025. PMID 20040394.
^ Vats ID, Chaudhary S, Karar J, Nath M, Pasha Q, Pasha S (October 2009). "Endogenous peptide: Met-enkephalin-Arg-Phe, differently regulate expression of opioid receptors on chronic treatment". Neuropeptides. 43 (5): 355–62. doi:10.1016/j.npep.2009.07.003. PMID 19716174.
^ ^a ^b ^c Thanawala V, Kadam VJ, Ghosh R (October 2008). "Enkephalinase inhibitors: potential agents for the management of pain". Current Drug Targets. 9 (10): 887–94. doi:10.2174/138945008785909356. PMID 18855623.
^ Lyons PJ, Callaway MB, Fricker LD (March 2008). "Characterization of carboxypeptidase A6, an extracellular matrix peptidase". The Journal of Biological Chemistry. 283 (11): 7054–63. doi:10.1074/jbc.M707680200. PMID 18178555.
^ Benuck M, Berg MJ, Marks N (1982). "Separate metabolic pathways for Leu-enkephalin and Met-enkephalin-Arg(6)-Phe(7) degradation by rat striatal synaptosomal membranes". Neurochemistry International. 4 (5): 389–96. doi:10.1016/0197-0186(82)90081-X. PMID 20487892.
^ William J. Kraemer; Alan David Rogol (29 August 2005). The endocrine system in sports and exercise. John Wiley & Sons. pp. 203–. ISBN 978-1-4051-3017-2. Retrieved 25 November 2011.

UpToDate Contents

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English Journal

Distribution of methionine-enkephalin in the minipig brainstem.

Sánchez ML, Vecino E, Coveñas R.SourceUniversity of Salamanca, Institute of Neurosciences of Castilla y León (INCYL), Laboratory of Neuroanatomy of the Peptidergic Systems, Salamanca, Spain. Electronic address: lisardosanchez8@gmail.com.
Journal of chemical neuroanatomy.J Chem Neuroanat.2013 Mar 25. pii: S0891-0618(13)00028-8. doi: 10.1016/j.jchemneu.2013.03.002. [Epub ahead of print]
We have studied the distribution of immunoreactive cell bodies and axons are containing methionine-enkephalin in the minipig brainstem. Immunoreactive axons were widely distributed, whereas the distribution of perikarya was less widespread. A high or moderate density of axons containing methionine-e
PMID 23538385

Music and biological stress dampening in mechanically-ventilated patients at the intensive care unit ward-a prospective interventional randomized crossover trial.

Beaulieu-Boire G, Bourque S, Chagnon F, Chouinard L, Gallo-Payet N, Lesur O.SourceSoins intensifs médicaux, département de Médecine, Université de Sherbrooke, Québec, Canada.
Journal of critical care.J Crit Care.2013 Mar 14. pii: S0883-9441(13)00012-9. doi: 10.1016/j.jcrc.2013.01.007. [Epub ahead of print]
PURPOSE: To evaluate the impact of slow-tempo music listening periods in mechanically ventilated intensive care unit patients.METHODS: A randomized crossover study was performed in a 16-bed, adult critical care unit at a tertiary care hospital. Still-sedated patients, mandating at least 3 more days
PMID 23499420

Links between breeding readiness, opioid immunolabeling, and the affective state induced by hearing male courtship song in female European starlings (Sturnus vulgaris).

Riters LV, Ellis JM, Angyal CS, Borkowski V, Cordes MA, Stevenson SA.SourceDepartment of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, United States. Electronic address: LVRiters@wisc.edu.
Behavioural brain research.Behav Brain Res.2013 Mar 5. pii: S0166-4328(13)00123-X. doi: 10.1016/j.bbr.2013.02.041. [Epub ahead of print]
Male courtship vocalizations represent a potent signal designed to attract females; however, not all females find male signals equally attractive. We explored the possibility that the affective state induced by hearing courtship vocalizations depends on the motivational state of a receiver. We used
PMID 23473880

Japanese Journal

高次元アルゴリズム (HA : Hamiltonian Algorithm) を用いた Enkephalin の立体構造の分子動力学的研究 : HAに現れる mixing 係数の効果

土屋恭平,寺前裕之,渡邊寿雄 [他],石元孝佳,長嶋雲兵
Journal of computer chemistry, Japan 6(5), 275-282, 2007-12-15
… Leu-EnkephalinとMet-Enkephalinの二種類のタンパク質を計算対象とした。 …
NAID 130000056887

高次元アルゴリズム(HA: Hamiltonian Algorithm)を用いたEnkephalinの立体構造の分子動力学的研究 : HAに現れるmixing 係数の効果

土屋恭平,寺前裕之,渡邊寿雄,石元孝佳,長嶋雲兵
Journal of Computer Chemistry, Japan 6(5), 275-282, 2007
… Leu-Enkephalin とMet-Enkephalin の二種類のタンパク質を計算対象とした。 …
NAID 120005520445

Immunohistochemical reactions of receptors to met-enkephalin, VIP, substance P, and CGRP located on Merkel cells in the rat sinus hair follicle

TACHIBANA Tamiko,NAWA Tokio
Archives of histology and cytology 68(5), 383-391, 2006-03-01
NAID 10017244418

Related Pictures

Preproenkephalin A Met-Enkephalin Met-Enkephalin (2D top frame; 3D bottom Description Met-enkephalin 1plx model 1 MET-ENKEPHALIN-ARG-PHE | 73024-95-0

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リンク元	「methionine enkephalin」
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「methionine enkephalin」

Met-enkephalin
Names
	IUPAC name (2S)-2-[[(2S)-2-[[2-[[2-[[(2S)-2-Smino-3-(4-hydroxyphenyl)propanoyl]amino]acetyl]amino]acetyl]amino]-3-phenylpropanoyl]amino]-4-methylsulfanylbutanoic acid
	Other names [Methionine]enkephalin; L-Tyrosylglycylglycyl-L-phenylalanyl-L-methionine
Identifiers
CAS Number	58569-55-4
ChEMBL	ChEMBL13786
ChemSpider	391597
EC Number	261-335-8
IUPHAR/BPS	1614
Jmol 3D model	Interactive image; Interactive image
KEGG	C11684
MeSH	Enkephalin,+Methionine
PubChem	443363
	InChI InChI=1S/C27H35N5O7S/c1-40-12-11-21(27(38)39)32-26(37)22(14-17-5-3-2-4-6-17)31-24(35)16-29-23(34)15-30-25(36)20(28)13-18-7-9-19(33)10-8-18/h2-10,20-22,33H,11-16,28H2,1H3,(H,29,34)(H,30,36)(H,31,35)(H,32,37)(H,38,39) Key: YFGBQHOOROIVKG-UHFFFAOYSA-N ;
	SMILES CSCCC(NC(=O)C(Cc1ccccc1)NC(=O)CNC(=O)CNC(=O)C(N)Cc1ccc(O)cc1)C(O)=O ; CSCCC(NC(=O)C(CC1=CC=CC=C1)NC(=O)CNC(=O)CNC(=O)C(N)CC1=CC=C(O)C=C1)C(O)=O ;
Properties
Chemical formula	C27H35N5O7S
Molar mass	573.67 g·mol−1
log P	0.607
Acidity (pKa)	3.234
Basicity (pKb)	10.763
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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