A cyclic hexapeptide, cyclo-pentaglycyl-L-lysyl hydrochloride (II L), has been synthesized in an attempt to obtain fundamental information about the syntheses of cyclic peptides; it has also been subjected to the action of trypsin. p-Methoxybenzyloxycarbonyltriglycyl-ε- benzyloxycarbonyl-L-lysylglycylglycine (XX) has been prepared by the saponification of the di-N-blocked hexapeptide ester which had been obtained by the condensation of p- ...