Spermine binding to liver mitochondria deenergized by ruthenium red plus either FCCP or antimycin A

Thermodynamic analysis of spermine binding to mitochondria treated with ruthenium red and deenergized with either FCCP or antimycin A confirms the presence of two polyamine binding sites, S-1 and S-2, both with monocoordination, as previously observed in energized mitochondria [Dalla Via et al., Biochim, Biophys. Acta 1284 (1996) 247-252], Both sites undergo a marked change in binding capacity and binding affinity upon mitochondrial deenergization. This change is most likely responsible for the incomplete or delayed spermine-mediated inhibition of the permeability transition induced in deenergized mitochondria. (C) 1998 Federation of European Biochemical Societies.