A cyclic heptapeptide, c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yumumensis French (M), was synthesized by solution method for the first time. Protected heptapeptide Z-Gly-Ile-Pr...A cyclic heptapeptide, c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yumumensis French (M), was synthesized by solution method for the first time. Protected heptapeptide Z-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OBzl was synthesized with 3-(diethoxy-phosphoryloxy)-l,2,3-benzotriazin-4(3H)-one (DEPBT) as a coupling reagent. After deprotection of benzyl and benzyloxycarbonyl groups, a free linear heptapeptide H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH was cyclized in DMF (2 × 10?3 mol/L) in the presence of nine different metal ions, i. e., Li+, Na+, K+, Cs+, Mg2+, Ca2+, Bai2+, Nr2+ and Cr5+ respectively, using DEPBT as a coupling reagent. Univalent metal ion Cs+ enhanced both the cyclization yield and cyclization rate of H-Gly-De-Pro-Tyr-Ile-Ala-AlaOH, while some bivalent metal ions, such as Mg2+, Ca2+ and Ni2+ decreased the yields of c (Gly-Ile-Pro-Tyr-De-Ala-Ala) drastically. Trivalent metal ion Cr3+ even inhibited the cyclization reaction completely.展开更多
文摘A cyclic heptapeptide, c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yumumensis French (M), was synthesized by solution method for the first time. Protected heptapeptide Z-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OBzl was synthesized with 3-(diethoxy-phosphoryloxy)-l,2,3-benzotriazin-4(3H)-one (DEPBT) as a coupling reagent. After deprotection of benzyl and benzyloxycarbonyl groups, a free linear heptapeptide H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH was cyclized in DMF (2 × 10?3 mol/L) in the presence of nine different metal ions, i. e., Li+, Na+, K+, Cs+, Mg2+, Ca2+, Bai2+, Nr2+ and Cr5+ respectively, using DEPBT as a coupling reagent. Univalent metal ion Cs+ enhanced both the cyclization yield and cyclization rate of H-Gly-De-Pro-Tyr-Ile-Ala-AlaOH, while some bivalent metal ions, such as Mg2+, Ca2+ and Ni2+ decreased the yields of c (Gly-Ile-Pro-Tyr-De-Ala-Ala) drastically. Trivalent metal ion Cr3+ even inhibited the cyclization reaction completely.
