Hydrophobic interaction approximate measure

Recently, considerable progress has been made on the calculation of electrostatic and hydrophobic interactions in biochemical systems 189 19 >. We can expect such calculations to become common for protein-solid surface interactions. Thus we can expect approximate values for the adsorption energy in selected systems to appear in the near future. The problem of time-dependent conformational adaptation of the protein to the surface (and vice versa) will be much more difficult. Initially, we will have to resort to crude measures of the structural stability of a protein, such as the temperature at which thermal denaturation occurs, the urea molar concentration for solution denaturation, etc. One or more of the models given in Fig. 13 should apply. 

Determination of the thermodynamic parameters for the transfer of non-polar organic compounds from aqueous to non-aqueous phases has been extensively used to estimate the free energy changes involved in hydrophobic interactions (Nemethy, 1967 Jencks, 1969). The experimental difficulties involved in the accurate determination of solubilities together with the approximations necessitated by limiting the measurements to simple organic compounds are the inherent disadvantages of this model. 

As shown in Figure 5.34, in the interactions among carboxylates while under the influence of increasing numbers of hydrophobic residues, pK pKo, but rather pK = pKo + ApK, that is, the pKa shifts of section 5.7.8. Furthermore, it is assumed that when one chain starts to ionize, due to the positive cooperativity, it completely ionizes before the next chain starts such that, to an adequate approximation, the experimentally measurable degree of ionization, a =... 

---