α-Endorphin (alpha-endorphin) is an endogenous opioid peptide with a length of 16 amino acids, and the amino acid sequence: Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr.[1] With the use of mass spectrometry, Nicholas Ling was able to determine the primary sequence of a-endorphin.[2]
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3D model (JSmol)
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| C77H120N18O26S | |
| Molar mass | 1745.97 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Relation to beta- and gamma-endorphin
editEndorphins are generally known as neurotransmitters that are released when the body goes into pain.[3] The three endorphins that play a role in this response are α-endorphin, β-endorphin (beta-endorphin), and γ-endorphin (gamma-endorphin) which are all derived from the same polypeptide known as pro-opiomelanocortin.[3] Although all play roles as neurotransmitters, the specific effects of all three differ. The most studied endorphin of the three is β-endorphin. α-Endorphins are known to contain one less amino acid than γ-endorphins, differing by a single leucine amino acid at the terminal end.[4] Although this may seem minor, It allows them to have vastly different effects. Studies found that γ-endorphins and α-endorphins have opposite effects which allow them to help maintain a level of homeostasis within the brain and behavior of animals.[5] All of the specific effects on the body of α-endorphins are not yet fully studied nor fully understood by the science community. However, some studies suggest that these endorphins behave similarly to amphetamines.[6] Similarly, other studies agree that Alpha-endorphins effects are similar to psychostimulant drugs.[6]
Ranking based length, α-endorphins are the shortest with 16 amino acid residues.[3] Meanwhile, the β-endorphin has the longest chain which begins with the same 16 amino acids as α-Endorphins: Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr.[3] The same sequence is also present in γ-endorphin.[3] The beginning Tyr-Gly-Gly-Phe-Met chain is also known as the N-terminal pentapeptide opioid sequence.[3] With such configuration, endorphins act as agonists to opioid receptors in the brain.[3]
Effects on behavior
editStudies have shown that α-endorphin is the strongest peptide in delaying avoidance behaviors.[7] α-Endorphin has the same C-terminal sequence of β-LPH, allowing these peptides to have a high affinity for opiate binding sites.[7] Even a slight difference in the C-terminal amino acid can have drastic effects on avoidance behavior.[7] The importance in sequencing determines the function of the endorphin.[7] When an N-terminal amino acid such as tyrosine is removed, there seems to be no significant impacts on avoidance behavior.[7] However, when there are adjustments to the C-terminal sequence, like removing β-LPH 61-65; activity of the endorphin decreases.[7]
See also
editReferences
edit- ^ Hazum E, Chang KJ, Cuatrecasas P (September 1979). "Specific nonopiate receptors for beta-endorphin". Science. 205 (4410): 1033–1035. Bibcode:1979Sci...205.1033H. doi:10.1126/science.224457. PMID 224457.
- ^ Guillemin R (1977). "The expanding significance of hypothalamic peptides, or, is endocrinology a branch of neuroendocrinology?". Recent Progress in Hormone Research. Proceedings of the 1976 Laurentian Hormone Conference. 33. Elsevier: 1–28. doi:10.1016/b978-0-12-571133-3.50008-8. ISBN 978-0-12-571133-3. PMID 20649.
- ^ a b c d e f g Chaudhry SR, Gossman W (2021). "Biochemistry, Endorphin". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID 29262177.
- ^ Koob GF, Bloom FE (October 1982). "Behavioral effects of neuropeptides: endorphins and vasopressin". Annual Review of Physiology. 44 (1): 571–582. doi:10.1146/annurev.ph.44.030182.003035. PMID 7041806.
- ^ Wiegant VM, Ronken E, Kovács G, De Wied D (1992). Endorphins and schizophrenia. Progress in Brain Research. Vol. 93. pp. 433–53. PMID 1480761.
- ^ a b Burbach JP, Loeber JG, Verhoef J, Wiegant VM, de Kloet ER, de Wied D (January 1980). "Selective conversion of beta-endorphin into peptides related to gamma- and alpha-endorphin". Nature. 283 (5742): 96–97. Bibcode:1980Natur.283...96B. doi:10.1038/283096a0. PMID 7350533. S2CID 4340549.
- ^ a b c d e f de Wied D (1981-01-01). "Neuropeptides in Normal and Abnormal Behavior". In Stark E, Makara GB, Ács Z, Endrőczi E (eds.). Endocrinology, Neuroendocrinology, Neuropeptides. Pergamon. pp. 23–38. doi:10.1016/b978-0-08-026827-9.50006-8. ISBN 978-0-08-026827-9.