Tang Yan-chun, Xie Hai-Bo, Tian Gui-ling, Ye Yun-hua
Structural Biology and Biochemistry, Hospital for Sick Children, Toronto, Ontario, Canada.
J Pept Res. 2002 Aug;60(2):95-103. doi: 10.1034/j.1399-3011.2002.201000.x.
Three cyclic peptides - cyclo(GlyAlaTyrLeuAla), cyclo(GlyProTyrLeuAla) and cyclo(GlyTyrGlyGlyProPhePro) - isolated and identified from medicinal herbs were chosen as model cyclic peptides to study the influence of the linear precursors and coupling reagents on cyclization. The 17 linear precursors of these three cyclic peptides were synthesized and cyclized using 3-(diethoxyphosphoryloxy)-(1-3)-benzotriazin-4 (3H)-one (DEPBT) as the major coupling reagent. The present work shows that: (i) the effects of linear peptide precursors on the cyclization are complex but some guidelines for choosing suitable precursor for cyclization could be considered; and (ii) DEPBT results in a higher cyclization yield compared with other coupling reagents. In addition, it was confirmed that peptides containing alternating D and L residues favor cyclization.
