High free energy of lipid/protein interaction in biological membranes.

The free energy of lipid/protein interaction in biological membranes is still unknown although extensive partitioning and modelling studies have revealed many partial energetic increments. Multiple site binding kinetics are now applied to four well-studied functional membrane proteins, and mean free energy values (+/-S.D.) of -4.23+/-0.49 kcal/mol for single lipid binding sites and of -89.7+/-35.4 kcal/mol for complete lipid substitution are obtained. These high free energy values point to an important bioenergetic role of lipid/protein interaction in membrane functions.