α-Endorphin is an

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, ...

opioid peptide Opioid peptides are peptides that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but th ...

with a length of 16 amino acids, and the

amino acid sequence Protein primary structure is the linear sequence of amino acids in a peptide or protein. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end. Protein biosynthesi ...

: Tyr-

Gly Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid (carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinogeni ...

-Gly- Phe- Met- Thr-

Ser Ser or SER may refer to: Places * Ser, a village in Bogdand Commune, Satu Mare County, Romania * Serpens (Ser), an astronomical constellation of the northern hemisphere * Serres, known as Ser in Serbian, a city in Macedonia, Greece Organizatio ...

- Glu- Lys-Ser-

Gln Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutra ...

-Thr-

Pro Pro is an abbreviation meaning " professional". Pro, PRO or variants thereof may also refer to: People * Miguel Pro (1891–1927), Mexican priest * Pro Hart (1928–2006), Australian painter * Mlungisi Mdluli (born 1980), South African retired ...

- Leu- Val-Thr. With the use of mass spectrometry, Nicholas Ling was able to determine the primary sequence of a-endorphin.

Relation to beta- and gamma-endorphin

Endorphins Endorphins (contracted from endogenous morphine) are chemical signals in the brain that block the perception of pain and increase feelings of wellbeing. They are produced and stored in an area of the brain known as the pituitary gland. Hist ...

are generally known as neurotransmitters that are released when the body goes into pain. The three endorphins that play a role in this response are Alpha-endorphins, Beta-endorphins, and Gamma-endorphins which are all derived from the same polypeptide known as

pro-opiomelanocortin Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is synthesized in corticotrophs of the anterior pituitary from the 267-amino-acid-long polypeptide precursor pre-pro-opiomelanocortin (pre-POMC), by the r ...

. Although all play roles as neurotransmitters, the specific effects of all three differ. The most studied endorphin of the three is Beta-endorphin. Alpha-endorphins are known to contain one less amino acid than gamma endorphins, differing by a single leucine amino acid at the terminal end. Although this may seem minor, It allows them to have vastly different effects. Studies found that Gamma-endorphins and Alpha-endorphins have opposite effects which allow them to help maintain a level of homeostasis within the brain and behavior of animals. All of the specific effects on the body of Alpha endorphins are not yet fully studied nor fully understood by the science community. However, some studies suggest that these endorphins behave similarly to amphetamines. Similarly, other studies agree that Alpha-endorphins effects are similar to psychostimulant drugs. Ranking based on length, alpha endorphins fall as the shortest chain with 16 amino acids. Meanwhile, the beta-endorphin has the longest chain consisting of the first 16 amino acids to be the same sequence chain of the alpha-endorphin: Tyr-

-Gly- Phe- Met- Thr-

- Glu- Lys-Ser-

-Thr-

- Leu- Val-Thr. The same sequence is also present in the gamma-endorphin. The beginning Tyr-Gly-Gly-Phe-Met chain is also known as N-terminal pentapeptide opioid sequence. With such configuration, endorphins act as agonist to opioid receptors in the brain.

Effects on behavior

Studies have shown that α-endorphin is the strongest peptide in delaying avoidance behaviors. Alpha Endorphin has C-terminal sequence of β-LPH, allowing these peptides to have a high affinity for opiate binding sites. Even a slight difference in C-terminal amino acid can have drastic effects on avoidance behavior. The importance in sequencing determines the function of the endorphin. When an N-terminal amino acid such as tyrosine is removed, there seems to be no significant impacts on avoidance behavior. However, when there are adjustments to the C-terminal sequence, like removing β-LPH 61-65; activity of the endorphin decreases.

References

Neuropeptides Opioid peptides {{biochemistry-stub

Relation to beta- and gamma-endorphin

Effects on behavior

See also

References