PROTONOPHORIC ACTIVITY OF NADH COENZYME-Q REDUCTASE AND ATP SYNTHASE IN COUPLED SUBMITOCHONDRIAL PARTICLES FROM HORSE PLATELETS

A method to prepare coupled submitochondrial particles from horse plat elets is described. The method allowed us to study the protonophoric a ctivities of both complex I and complex V following the fluorescence q uenching of the monoamine 9-amino-6-chloro-2 methoxyacridine (ACMA), a probe highly sensitive to the generation of a transmembrane Delta pH. We carried out a kinetic analysis of each enzyme complex studying the proton translocation and the electron transfer activities of complex I as well as the proton translocation and the ATP hydrolytic activitie s of complex V. A micromethod to prepare coupled submitochondrial part icles from platelets might be useful to investigate cell bioenergetic damage occurring in mitochondrial diseases and ageing. (C) 1997 Academ ic Press.