Amino Acids and Peptides. Part 224. Analogues of Cholecystokinin Methylated in the Side Chain of Carboxyterminal Phenylalanine. -The Boc-cholecystokinin-7 (Boc-CCK-7) analogues which are modified by phenylalanine derivatives containing 2-, 4-, 4,6-or 2,4,6-methylated aromatic side-chains behave as full agonists of CCK-8. The peptides with (L) form of the methylated phenylalanines are found to be as potent as CCK-8, whereas the (D) analogues exhibit lower potency. This indicates that the phenylalanine residue takes part in biological activity transduction only. -(HLAVACEK, J.; PIRKOVA, J.; MAJER, P.; ZERTOVA, M.; MALETINSKA, L.; SLANINOVA, J.; Collect.