Thermodynamic nonideality in macromolecular solutions : evaluation of parameters for the prediction of covolume effects

摘要: Second virial coefficients and hence covolumes for self-interaction of five proteins, viz. ribonuclease, ovalbumin, bovine serum albumin, catalase α-crystallin, have been determined by analyzing the concentration dependence partition coefficient obtained from frontal chromatographic studies on either Fractogel TSK HW55 or porous glass beads. The resulting estimates effective radii essentially duplicate their Stokes counterparts thereby provide further justification assuming approximate identity thermodynamic hydrodynamic hydrated globular proteins. Gel evaluation second protein/dextran systems has led to elimination sphere/sphere model as a valid description space-filling effects in protein/polymer mixtures, since it does not predict observed independence covolume, expressed per unit mass polymer, upon size polymer. This requirement is met sphere/rod [Edmond, E. & Ogston, A. G. (1968) Biochem. J. 109, 569–576] also sphere/flexiblesegment [Hermans, (1982) Chem. Phys. 77, 2193–2203]. Furthermore, similar effect solute radius covolume interaction with dextran T70 attest adequacy predicting nonideality arising inclusion dextrans protein solutions, relevant calibration model.