title: A comparison of the phosphorylation potential and electrochemical proton gradient in mung bean mitochondria and phosphorylating sub-mitochondrial particles.
abstract: The phosphorylation potential (delta Gp) and the electrochemical proton gradient (delta muH+) normally maintained during respiration or ATP hydrolysis by mung bean hypocotyl mitochondria and phosphorylating sub-mitochondrial particles have been investigated. Phosphorylation potential experiments using safranine and oxonol-VI, as membrane potential markers for mitochondria and sub-mitochondrial particles, respectively, suggest that the 'null point' delta Gp (i.e., the phosphorylation potential at which no change in optical signal occurred) corresponds to a value of 15.2 +/- 0.7 kcal/mol in mitochondria and 11.2 +/- 0.3 kcal/mol in sub-mitochondrial particles. The value of delta muH+ generated by the hydrolysis of ATP was estimated using ion distribution techniques. In each case a rapid centrifugation technique was used to separate the organelle from the suspending medium. The total delta muH+ generated in each case was approx. 200 mV being composed of both membrane potential and pH components. A comparison of delta muH+ with delta Gp indicates that the apparent H+/ATP ratio in mung bean mitochondria is 3.4 +/- 0.2 while in phosphorylating sub-mitochondrial particles it is 2.2 +/- 0.1.
mesh_terms: D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010766:Phosphorylation; D010944:Plants / Q000378:metabolism*; D013367:Submitochondrial Particles / Q000378:metabolism*; D013861:Thiocyanates / Q000494:pharmacology
chemical_list: D009840:Oligomycins; D013861:Thiocyanates; D009243:NAD; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone