Electrostatics in Macromolecular Solutions - Food Colloids: Self-Assembly and Material Science - page 152

Figure 16 The free energy of interaction A(R) between the centres of mass of lysozyme
and the polyanion at pH ¼ pI. The four curves correspond to the different sets
of simulations mentioned in the text: (a) lysozyme + polyanion; and (b) a -
lactalbumin + polyanion

Figure 16(b) shows that the polyanion interacts more strongly with
a-lactalbumin than with lysozyme. For a-lactalbumin the regulation term
increases the depth of the minimum from

6 kT. We note that
the dipolar protein (C) shows a stronger interaction than the protein with a
detailed but fixed charge distribution (B). This means that the ion-quadrupole
interactions, etc., add repulsive contributions to the overall

B 4to B

interaction

potential.