Energy-dependent dissociation of ATP from high affinity catalytic sites of beef heart mitochondrial adenosine triphosphatase
Incubation of (gamma-TSP)ATP with a molar excess of the membrane-bound form of mitochondrial ATPase (F1) results in binding of the bulk of the radioactive nucleotide in high affinity catalytic sites (Ka = 10(12) M-1). Subsequent initiation of respiration by addition of succinate or NADH is accompanied by a profound decrease in the affinity for ATP. About one-third of the bound radioactive ATP appears to dissociate, that is, the (gamma-TSP)ATP becomes accessible to hexokinase. The NADH-stimulated dissociation of (gamma-TSP)ATP is energy-dependent since the stimulation is inhibited by uncouplers of oxidative phosphorylation and is prevented by respiratory chain inhibitors. The rate of the energy-dependent dissociation of ATP that occurs in the presence of NADH, ADP, and Pi is commensurate with the measured initial rate of ATP synthesis in NADH-supported oxidative phosphorylation catalyzed by the same submitochondrial particles. Thus, the rate of dissociation of ATP from the high affinity catalytic site of submitochondrial particles meets the criterion of kinetic competency under the conditions of oxidative phosphorylation. These experiments provide evidence in support of the argument that energy conserved during the oxidation of substrates by the respiratory chain can be utilized to reduce the very tight binding of product ATP in high affinity catalytic sites and to promote dissociation of the nucleotide.
- Research Organization:
- Public Health Research Institute of the City of New York, NY
- OSTI ID:
- 6336087
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 25
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mapping of the nucleotide-binding sites in the ADP/ATP carrier of beef heart mitochondria by photolabeling with 2-azido(. cap alpha. -/sup 32/P)adenosine diphosphate
Effect of nitration and D/sub 2/O on the kinetics of beef heart mitochondrial adenosine triphosphatase
Related Subjects
ATP
BIOCHEMICAL REACTION KINETICS
AFFINITY
ATP-ASE
CATTLE
HEART
HYDROLYSIS
IN VITRO
MITOCHONDRIA
NAD
NADH2
PHOSPHORUS 32
PHOSPHORYLATION
RESPIRATION
TRACER TECHNIQUES
ACID ANHYDRASES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CHEMICAL REACTIONS
COENZYMES
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DOMESTIC ANIMALS
ENZYMES
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LYSIS
MAMMALS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
PHOSPHOHYDROLASES
PHOSPHORUS ISOTOPES
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
SOLVOLYSIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques