The interaction between small peptide derivatives and cyclodextrin dimers was studied by fluorescence polarization method. Four small peptide derivatives, Adm-Lys (Adm)-Arg-Arg 5; Adm-Lys (Adm)-D-Arg-D- Arg 6; Adm-Cha-Arg-Arg 7; Adm-Cha-D-Arg 8 (where Arg, Lys, Cha and Adm are the abbreviation of arginine, lysine, β-cyclohexylalanine and 1- carboxyl-adamantane, respectively) were used as guest molecules, and four cyclodextrin dimers 1 ～ 4, bridged with derivatives of aspartic acid; glutamic acid; (1R, 3R)-1-aminocyclobutane-cis-1, 3-dicarboxylic acid, (1R, 3R)-1-aminocyclopentane-cis-1, 3-dicarboxylic acid respectively, were used as host molecules. The binding constants (K_b) and thermodynamic parameters (△G°，△H°，△S°) of these host-guest systems were reported. The data showed that the complexation was accompanied by large negative changes in enthalpy and the bonding affinity of host to guest varied with the spatial arrangement of non- penetrating groups, the structure and properties of penetrating group in guest molecules. The molecular recognition ability of cyclodextrin dimer to the peptide derivatives was discussed based on the values of - △△G_(DL)°and K_L/K_D. According to the good linear relationship of △ H° versus T△S°, enthalpy-entropy compensation of the complexation of labeled cyclodextrin dimers with several small peptide derivatives was investigated.

Key words: CYCLODEXTRIN, AMINO ACID, POLYPEPTIDE, CLATHRATES, THERMODYNAMIC PROPERTIES