Kreil G, Umbach M, Brantl V, Teschemacher H
Life Sci. 1983;33 Suppl 1:137-40. doi: 10.1016/0024-3205(83)90463-0.
beta-Casomorphins (beta-CMs), although known to be highly resistant to proteolytic enzymes, are demonstrated to be rapidly degraded in bovine or rat plasma. Degradation of these peptides consisting of the amino acid sequence TYR-PRO-PHE-PRO-GLY-PRO-ILE and C-terminally shortened fragments thereof, may be due to an enzyme identical with or similar to the dipeptidyl-peptidase IV (DP IV) which is known to cleave dipeptide fragments from the N-terminus of peptides after proline residues. This assumption is compatible with the finding that beta-casomorphin (beta-CM) analogues in which the proline residue in position two has been replaced by D-alanine, seem to be completely resistant to enzymatic attack in the plasma.
β-酪蛋白吗啡肽（β-CMs）虽然已知对蛋白水解酶具有高度抗性，但在牛或大鼠血浆中却能迅速降解。这些由氨基酸序列TYR-PRO-PHE-PRO-GLY-PRO-ILE及其C端缩短片段组成的肽的降解，可能是由于一种与二肽基肽酶IV（DP IV）相同或相似的酶，已知该酶能从脯氨酸残基后肽的N端切割二肽片段。这一假设与以下发现相符：在第二位的脯氨酸残基被D-丙氨酸取代的β-酪蛋白吗啡肽（β-CM）类似物，似乎对血浆中的酶攻击完全具有抗性。
