Opioid peptide

Brain opioid peptide systems are known to play an important role in motivation, emotion, attachment behaviour, the response to stress and pain, control of food intake, and the rewarding effects of alcohol and nicotine.

Opioid-like peptides may also be absorbed from partially digested food (casomorphins, exorphins, and rubiscolins).

Sequence analysis reveals that the conserved N-terminal region of the precursors contains 6 cysteines, which are probably involved in disulfide bond formation.

[1] The human genome contains several homologous genes that are known to code for endogenous opioid peptides.

Exorphins mimic the actions of endorphins by binding to and activating opioid receptors in the brain.

Structural correlation between met-enkephalin , an opioid peptide (left) , and morphine , an opiate drug (right)