Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (08): 2103-2108.doi: 10.3866/PKU.WHXB20100821

• THERMODYNAMICS,THERMOCHEMISTRY AND SOLUTION CHEMISTRY • Previous Articles     Next Articles

Heterotactic Enthalpy of the Interaction between Protein Model Compounds and Diols in Aqueous Solutions at 310.15 K

ZHU Yan1, PANG Xian-Hong1, YU Li2   

  1. 1. Department of Chemistry and Chemical Engineering, Taishan Medical University, Taian 271016, Shandong Province, P. R. China;
    2. Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, P. R. China
  • Received:2010-03-12 Revised:2010-04-22 Published:2010-07-23
  • Contact: ZHU Yan E-mail:2004zy428@163.com
  • Supported by:

    The project was supported by the Doctoral Fund of the Ministry of Education of China (New Teachers Fund) (070422047) and Natural Scientific Foundation of Shandong Province, China (Z2007B03).

Abstract:

The enthalpies of mixing for model protein compounds (glycine, alanine, N,N-dimethyl formamide (DMF) and N,N-dimethyl acetamide (DMA)) with diols (1, 3-butanediol and 2, 3-butanediol) and their respective enthalpies of dilution in aqueous solutions at 310.15 K were determined by flow microcalorimetric measurements. Heterotactic enthalpic interaction coefficients (hxy, hxxy, hxyy) were obtained by analyzing these experimental results according to McMillan-Mayer theory. The results indicated that the hxy values were all positive with a dominant endothermic effect and the coefficients decreased according to the order of hxy(DMA)>hxy(Ala)>hxy(Gly)>hxy(DMF) and hxy(2,3-butanediol)>hxy(1,3-butanediol). Based on these results, we discussed solute-solute and solute-solvent interactions with regards to the influence of the relative position of the diol functional groups on the value of hxy. We found that the hydrogen bonds between DMF or DMA and the diols were strong, and because of the good polarizability of DMF's resonance structure, hydrogen bonds between DMF and the diols were further strengthened.

Key words: Amino acid, DMF, DMA, Diol, Solute-solute interaction

MSC2000: 

  • O642