Α-Endorphin
Chemical compound
From Wikipedia, the free encyclopedia
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] Researchers at the Salk Institute were pioneers in isolating, sequencing, and synthesizing the peptides they named α- and γ-endorphin, and they determined that they had morphinomimetic activity[2]. With the use of mass spectrometry and dansyl-Edman methods, Nicholas Ling, one of the researchers from the Salk Institute, was able to determine the primary sequence of α-endorphin.[3]
| |
 | |
| Identifiers | |
|---|---|
3D model (JSmol) |
|
| ChEMBL | |
| ChemSpider | |
PubChem CID |
|
| |
| |
| Properties | |
| 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).
| |
Relation to beta- and gamma-endorphin
Endorphins are generally known as neurotransmitters that are released when the body goes into pain.[4] 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.[4] 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.[5] 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.[6] 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.[7] Similarly, other studies agree that Alpha-endorphins effects are similar to psychostimulant drugs.[7]
Ranking based length, α-endorphins are the shortest with 16 amino acid residues.[4] 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.[4] The same sequence is also present in γ-endorphin.[4] The beginning Tyr-Gly-Gly-Phe-Met chain is also known as the N-terminal pentapeptide opioid sequence.[4] With such configuration, endorphins act as agonists to opioid receptors in the brain.[4]
Effects on behavior
Studies have shown that α-endorphin is the strongest peptide in delaying avoidance behaviors.[8] α-Endorphin has the same C-terminal sequence of β-LPH, allowing these peptides to have a high affinity for opiate binding sites.[8] Even a slight difference in the C-terminal amino acid can have drastic effects on avoidance behavior.[8] The importance in sequencing determines the function of the endorphin.[8] When an N-terminal amino acid such as tyrosine is removed, there seems to be no significant impacts on avoidance behavior.[8] However, when there are adjustments to the C-terminal sequence, like removing β-LPH 61-65; activity of the endorphin decreases.[8]