Enzymatic Synthesis of Cholecystokinin-octapeptide

Abstract

Cholecystokinin-octapeptide was synthesized by enzymatic condensations of three fragments, without side-chain protection, except for Tyr. Fmoc-Asp-Tyr (SO₃Ba1/2)-OH, prepared by the concerted action of proteases, followed by pyridinium trifluoroacetylsulfate treatment, was used as the N-terminal fragment. In the final step, the Nα-Fmoc group employed as a sole protecting group was easily removed by base treatment without affecting the SO₃ moiety.