b-Casomorphin (1-3), with the sequence H2N-Tyr-Pro-Phe-OH, is an opioid-like active tripeptide obtained from the enzymatic digestion of bovine β-casein. Due to genetic diversity among cattle populations, β-casein exists in 17 different variants. In A1 β-casein, the presence of histidine at position 67 makes the peptide bond between residues 66 and 67 more susceptible to enzymatic cleavage, resulting in the release of a specific heptapeptide known as β-casomorphin-7 (BCM-7). BCM-7 is the most common and earliest studied bioactive peptide derived from bovine β-casein. b-Casomorphin (1-3), corresponding to the N-terminal tripeptide of BCM-7, is considered the core active fragment for opioid receptor recognition. b-Casomorphin (1-3) is generally not used as an opioid receptor agonist in cell and animal studies like BCM-7 and is more commonly used for receptor binding and structure–activity relationship studies within the β-casomorphin family[1][2].
References:
[1] Gard F, Flad LM, Weißer T, Ammer H, Deeg CA. Effects of A1 Milk, A2 Milk and the Opioid-like Peptide β-Casomorphin-7 on the Proliferation of Human Peripheral Blood Mononuclear Cells. Biomolecules. 2024; 14(6):690.
[2] Jinsmaa, Y, and M Yoshikawa. “Enzymatic release of neocasomorphin and beta-casomorphin from bovine beta-casein.” Peptides vol. 20,8 (1999): 957-62.