[Evaluation of changes in free energy of proteins and biomembranes under pH-induced conformational transitions. Coupling membranes of peak chloroplasts].

It was shown that changes in the free energy during pH-induced conformational transitions can be calculated from the buffer spectrum of the biopolymer. These changes are similar to those of the chemical potential of cooperatively protonating groups (delta Go = 2,3 RT (pKt--pKi)Nt) and can be determined independently for each transition of the complex object. Consequently, in case of biomembranes with the ionic strength greater than or equal to 0,1 it is possible to determine not only the maximal efficiency of each transition according to the formula magnitude of delta Go congruent to 2,3 RTNt, but also that of the membrane component which initiates the given transition. Thus, a study of the photo-dependent buffer spectrum of the coupling membranes of chloroplasts showed that in the membrane the ATPase complex performs a reversible conformational transition within the pH region of photophosphorylation with the energy of 100--130 kcal/mol for the coupling factor or 190--260 cal/mol for the chlorophyll.