Thermodynamic solvation of a series of homologous α-amino acids in non-aqueous mixture of ethylene-glycol and N,N-dimethyl formamide
- 1
- 2
- 3 Dept. of Chemistry, Shibpur Dinabundhoo Institution(College), Howrah, India
Abstract
Standard free energies (ΔG<sup>0</sup><sub>t</sub>(i) ) and entropies (ΔS<sup>0</sup><sub>t</sub>(i)) of transfer of some homologous α-amino acids viz. glycine (gly), dl-alanine (ala), dl-α-amino butyric acid (aba) and dl-nor-valine (nor-val) from protic ethylene glycol (EG) to dipolar aprotic N,N-dimethyl formamide (DMF) have been evaluated from solubility measure-ments at five equidistant temperatures i.e from 15 to 35<sup>0</sup>C. The observed ΔG<sup>0</sup><sub>t</sub>(i) and TΔS<sup>0</sup><sub>t</sub>(i) Vs composition profiles are complicated because of the various interaction effects. The chemical effects of the transfer Gibbs energies (ΔG<sup>0</sup><sub>t.ch</sub>(i)) and entropies of transfer (ΔS<sup>0</sup><sub>t.ch</sub>(i)) have been obtained after elimination of cavity effect, estimated by the scaled particle theory and dipole-dipole interaction effects, estimated by the use of Keesom-orientation expression. The chemical contributions of transfer energetics of homologous α-amino acids are guided by the composite effects of increased dispersion interaction, basicity and decreased acidity, hydrogen bonding effects and solvophobic solvation of ethylene glycol and N, N-dimethyl formamide mixed solvent as compared to that of reference solvent (ethylene glycol).
- Das, P., chatterjee, S. and Basu Mallick, I. (2004) Thermodynamic studies on amino acid solvation in some aqueous alcohols. Journal of Chinese Chemical Society, 51, 1-6.
- Bani pal, T.S., Singh. G. and Lark, B.S. (2001) Partial molar volumes of transfer of some amino acids from water to aqueous glycerol solutions at 25?C. Journal of Solution Chemistry, 30, 657.
- Lapamje, S. (1978) In physico-chemical aspects of proteins denaturation. Wiley Intercience, New York, 241.
- Islam, M.N. and Wadi, R.K. (2001) Thermodynamics of transfer of amino acids from water to aqueous sodium sulfate. Physics and Chemistry of Liquids, 39, 77-84. doi:10.1080/00319100108030328
- K?seoglu, F., Kili?b, E. and Dogan, A. (2000) Studies on the Protonation Constants and Solvation of α-Amino Acids in Dioxan-Water Mixtures. 277, 243-246.
- Anfinsen, C.B and Seheraga, H.A. (1978) Experimental and theoretical aspects of protein folding. Advances in Protein Chemistry, 29, 205-300. doi:10.1016/S0065-3233(08)60413-1
- Reading, J.F., Watson, I.D. and Gavin, R.H. (1990) Thermodynamic properties of peptide solutions 5. Partial molar volumes of glycylglycine, glycyl-DL-leucine, and glycyl-DL-serine at 308.15 and 318.15 K. The Journal of Chemical Thermodynamics, 22, 159-165. doi:10.1016/0021-9614(90)90079-6
- Nozaki, Y. and Tanford, C. (1963) The solubilities of amino acids and related compounds in aqueous urea solutions. The Journal of Biological Chemistry, 238, 4074- 4081.
- Abu-Hamdiyyah, M. and Shehabuddin, A. (1982) Transfer enthalpies and entropies of amino acids from water to urea solutions. Journal of Chemical Engineering Data, 27, 74-76.
- Gekko, K. and Timasheff, S.N. (1981) Thermodynamic and kinetic examination of protein stabilization by glycerol. Biochemistry, 20, 4677. doi:10.1021/bi00519a024
- Sinha, R., Bhattacharya, S.K. and Kundu, K.K. (2005) Chemical transfer energetic of the –CH2–group in aqueous glycerol: Solvent effect on hydrophobic hydration and its three-dimensional structure. Journal of Molecular Liquids, 122, 95-103. doi:10.1016/j.molliq.2005.04.003
- Roy, S., Mahali. K. and Dolui, B.K. (2009) Thermodynamic studies of solvation a series of homologous α-amino acids in aqueous mixtures of protic ethylene glycol at 298.15?C. Biochemistry—An Indian Journal, 3, 63-68.
- Ganguly, S. and Kundu, K.K. (1993) Transfer energetic of some DNA and RNA bases in aqueous mixtures of urea and glycerol. Journal of Physical Chemistry, 97, 10862-10867. doi:10.1021/j100143a055