Α-Endorphin

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]

α-Endorphin

Identifiers
CAS Number	61512-76-3 Y
3D model (JSmol)	Interactive image
ChemSpider	17294814 N
PubChem CID	16138308
SMILES C[C@H]([C@@H](C(=O)N[C@@H](CO)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CO)C(=O)N[C@@H](CCC(=O)N)C(=O)N[C@@H]([C@@H](C)O)C(=O)N1CCC[C@H]1C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](C(C)C)C(=O)N[C@@H]([C@@H](C)O)C(=O)O)NC(=O)[C@H](CCSC)NC(=O)[C@H](CC2=CC=CC=C2)NC(=O)CNC(=O)CNC(=O)[C@H](CC3=CC=C(C=C3)O)N)O
Properties
Chemical formula	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). N verify (what is YN ?) Infobox references

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]

See also

• Endorphin
• Amphetamines