The convenience of the use of allosteric "probes" for the study of lipid--protein interactions in biological membranes: thermodynamic considerations.

One of the most commonly used methods to study enzyme (protein)-structure interactions at a more specific level is the use of the Arrhenius plots to detect the influence of the “environment” on the enzyme. We want to point out here that the use of a suitable “allosteric enzyme” would be a more sensitive method to detect influences of the environment than the study of Arrhenius plots. According to simple thermodynamic considerations, a change of more than 2.8 kcal/mol in the interaction between enzyme and membrane would be needed to give a noticeable change in the position of the break (T_i) of the corresponding Arrhenius plot. On the other hand, feeble changes in the membrane-enzyme interaction, of the order of 0·7–0·8 kcal/mol, would be enough to give a significant change in the values of n (Hill coefficient).