Acta Phys. -Chim. Sin. ›› 1996, Vol. 12 ›› Issue (01): 91-95.doi: 10.3866/PKU.WHXB19960120

• Note • Previous Articles    

Study on the Conformation of Three Cyclic Peptides and Their Correspondent Linear Peptides with CD Spectroscopy

Jiang Yun,Miao Zhen-Wei,Xu Xiao-Jie,Tang You-Qi   

  1. Institute of Physical Chemistry,Peking University,Beijing 100871
  • Received:1995-01-26 Revised:1995-06-30 Published:1996-01-15
  • Contact: Miao Zhen-Wei

Abstract:

We used CD spectroscopy to study the conformations of three cyclic peptides (CP10E: cyclo[Glu(OBz1)-Pro-Gly-Glu(OBzl)-Gly]2, CP10K: cyclo[Lys(Z)-Pro-Gly-Lys(Z)-Gly]2, CP12K: cyclo[Phe-Lys(Z)-Pro-Gly-Lys(Z)-Gly]2 and their correspondent linear peptides (LP10E: Boc-[Glu(OBzl)-Pro-Gly-Glu(OBzl)-Gly]2-OPac, LP10K: Boc-[Lys(Z)-Pro-Lys(Z)-Pro]2-OMe, LP 12K: Bao- [-Lys(Z)-Pro-Gly-Lys(Z)-Gly]2- OMe) in three solvents of different polarity (chloroform, acetonitrile, 2,2,2-triliuroethanol), and it was found that all of linear and cyclicpeptides exists asγ-turn conformation in chloroform, however, in TFE& CH3CN solutions, the three linear peptides are inβ Ⅱ-turn conformations. CP10E isβI-turn conformation, CP10K &CP12K exists in more than one types of turn conformations. On the basis of our experiments, it was concluded: 1) In the presence of conformational constrained amino acids short linear peptides form obvious secondary structure; 2)The solvent polarity has influence on the peptide conformation and this influence on linear peptides is greater than that on cyclic peptides; 3)The backbone of cyclic peptide has constraint effect on its conformation and makes the secondary structure of cyclic peptide different from that of its relative linear peptide. This information might give some cules in the design of bioactive peptides with different receptor selectivity.

Key words: Circular dichroism spectroscopy, Cyclic peptide, Linear peptide, Conformation