Voltage induced ATP synthesis and its implications for mitochondrial F/sub 0/F/sub 1/ ATPase
The F/sub 0/F/sub 1/ ATPase of the inner mitochondrial membrane catalyzes the conversion of a proton electrochemical energy into the chemical bond energy of ATP. To assess the role of the membrane potential (..delta..psi) in this process and to study the effect of very short pulses on ATP synthesis, a high voltage pulsation method was employed to induce a ..delta..psi of controlled magnitude and duration on a suspension of submitochondrial particles and F/sub 0/F/sub 1/ ATPase vesicles. Cyanide treated submitochondrial particles were exposed to electric pulses of 10-30 kV/cm magnitude (generating a peak ..delta..psi of 150-450 mV) and 1-100 ..mu..s duration. Net (/sup 32/P)ATP synthesis from (/sup 32/P)P/sub i/ and ADP was observed with maximal values of 410 pmol/mg.pulse for a 30 kV/cm-100..mu..s pulse. This corresponds to a yield of 10-12 moles of ATP per mole of F/sub 0/F/sub 1/ complex per pulse. As many as 4 nmole/mg were produced after pulsing the same sample 8 times. By varying the ionic strength of the suspending medium, and consequently the pulse width, it is clearly shown that the synthesis was electrically driven, and did not correlate with Joule heating of the sample. Titrations using specific inhibitors and ionophores were performed. The voltage induced ATP synthesis was 50% inhibited by 0.11 ..mu..g/ml of oligomycin and by 2.4 nmole/mg of N,N'-dicyclohexylcarbodiimide. Ionophores and uncouplers had varying degrees of inhibition. The dependence of ATP synthesis on pulse width was non-linear, exhibiting a threshold of 10..mu..s and a biphasic behavior above this value.
- Research Organization:
- Johns Hopkins Univ., Baltimore, MD (USA)
- OSTI ID:
- 5097937
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ATP
BIOSYNTHESIS
ATP-ASE
ENZYME ACTIVITY
IMIDES
BIOLOGICAL EFFECTS
ADP
CELL MEMBRANES
ELECTROCHEMICAL ENERGY CONVERSION
LABELLED COMPOUNDS
MITOCHONDRIA
PHOSPHORUS 32
PROTONS
TRACER TECHNIQUES
ACID ANHYDRASES
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CONVERSION
DAYS LIVING RADIOISOTOPES
ELEMENTARY PARTICLES
ENERGY CONVERSION
ENZYMES
FERMIONS
HADRONS
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MEMBRANES
NUCLEI
NUCLEONS
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
PHOSPHOHYDROLASES
PHOSPHORUS ISOTOPES
RADIOISOTOPES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques
560301 - Chemicals Metabolism & Toxicology- Cells- (-1987)