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Effects of deuterium on the kinetics of beef heart mitochondrial ATPase

Journal Article · · Arch. Biochem. Biophys.; (United States)
; ;
A study was done examining the steady-state kinetics of F1-catalyzed ATP and ITP hydrolyses in the presence or absence of D2O as a function of temperature. The steady-state kinetic parameters kcat and kcat/Km were obtained. For ATP hydrolysis, kcat/Km was independent of temperature in the presence or absence of D2O, while kcat/Km for ITP hydrolysis increased in both cases. The relative magnitudes of change of kcat and kcat/Km in the presence and absence of D2O over the temperature range studied were much different for the cases of ATP and ITP hydrolysis. A normal isotope effect was observed in plots of kcat H2O/kcat D2O versus temperature for ATP hydrolysis, which increased then leveled off as temperature increased. An inverse isotope effect at low temperatures changed to a normal isotope effect and increased dramatically as temperature increased during ITP hydrolysis. The results are discussed in terms of the nature and location of the rate-limiting steps in the reaction mechanisms.
Research Organization:
Department of Chemistry, University of Nebraska-Lincoln
OSTI ID:
6625782
Journal Information:
Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 231:2; ISSN ABBIA
Country of Publication:
United States
Language:
English

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Related Subjects

560172* -- Radiation Effects-- Nuclide Kinetics & Toxicology-- Animals-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID ANHYDRASES
ANIMALS
ATP-ASE
BODY
CARDIOVASCULAR SYSTEM
CATTLE
CELL CONSTITUENTS
DEUTERIUM
DOMESTIC ANIMALS
ENZYMES
HEART
HEAVY WATER
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROLASES
ISOTOPES
LIGHT NUCLEI
MAMMALS
MITOCHONDRIA
NUCLEI
ODD-ODD NUCLEI
ORGANOIDS
ORGANS
OXYGEN COMPOUNDS
PHOSPHOHYDROLASES
RADIONUCLIDE KINETICS
RUMINANTS
STABLE ISOTOPES
VERTEBRATES
WATER