Protein hydrolysates in animal nutrition: Industrial production, bioactive peptides, and functional significance

Table 5 Opioid peptides generated from the enzymatic hydrolysis of animal and plant proteins in the gastrointestinal tract

Source	Name of opioid peptide	Amino acid sequence
Milk casein	Bovine β-casomorphin 1–3	Tyr-Pro-Phe-OH
	Bovine β-casomorphin 1–4	Tyr-Pro-Phe-Pro-OH
	Bovine β-casomorphin 1–4, amide	Tyr-Pro-Phe-Pro-NH₂
	Bovine β-casomorphin 5	Tyr-Pro-Phe-Pro-Gly-OH
	Bovine β-casomorphin 7	Tyr-Pro-Phe-Pro-Gly-Pro-Ile-OH
	Bovine β-casomorphin 8	Tyr-Pro-Phe-Pro-Gly-Pro-Ile-Pro-OH^a
Gluten protein	Gluten exorphin A5	Gly-Tyr-Tyr-Pro-Thr-OH
	Gluten exorphin B4	Tyr-Gly-Gly-Trp-OH
	Gluten exorphin C	Tyr-Pro-Ile-Ser-Leu-OH
	Gliadorphin	Tyr-Pro-Gln-Pro-Gln-Pro-Phe-OH
Soybean protein	Soymorphin-5^b	Tyr-Pro-Phe-Val-Val-OH
	Soymorphin-5, amide	Tyr-Pro-Phe-Val-Val-NH₂
	Soymorphin-6	Tyr-Pro-Phe-Val-Val-Asn-OH
	Soymorphin-7	Tyr-Pro-Phe-Val-Val-Asn-Ala-OH
Spinach protein	Rubiscolin-5	Gly-Tyr-Tyr-Pro-OH
Spinach protein	Rubiscolin-6	Gly-Tyr-Tyr-Pro-Thr-OH

Adapted from Li-Chan [21], López-Barrios et al. [22], Shimizu and Son [35], Bah et al. [36], and Froetschel [42]
^aAnother form of bovine β-casomorphin 8 has histidine instead of proline in position 8, depending on whether the peptide is derived from A1 or A2 beta-casein
^bDerived from β-conglycinin β-subunit

ISSN: 2049-1891