Kinetics of the creatine kinase reaction in neonatal rabbit heart: An empirical analysis of the rate equation

Journal Article · Tue Mar 12 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00224a004· OSTI ID:5026453

McAuliffe, J J ^[1]; Perry, S B ^[2]; Brooks, E E ^[3]; Ingwall, J S ^[4]

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1. Univ. of Cincinnati College of Medicine, OH (United States)
2. Childrens Hospital, Boston, MA (United States)
3. Univ. of Cincinnati, OH (United States)
4. Brigham and Women's Hospital, Boston, MA (United States) Harvard Medical School, Boston, MA (United States)

Here the authors define the kinetics of the creatine kinase (CK) reaction in an intact mammalian heart containing the full rnage of CK isoenzymes. Previously derived kinetic constants were refit for the reaction occurring at 37C. Steady-state metabolite concentrations from {sup 31}P NMR and standard biochemical techniques were determined. {sup 31}P magnetization transfer data were obtained to determine unidirectional creatine kinase fluxes in hearts with differing total creatine contents and differing mitochondrial CK activities during KCl arrest and isovolumic work for both the forward reaction (MgATP synthesis) and reverse reaction (phosphocreatine synthesis). The NMR kinetic data and substrate concentrations data were used in conjunction with a kinetic model based on MM-CK in solution to determine the applicability of the solution-based kinetic models to the CK kinetics of the intact heart. The results indicated that no single set of rate equation constants could describe both the KCl-arrested and working hearts. Analysis of the results indicated that the CK reaction is rate limited in the direction of ATP synthesis, the size of the guanidino substrate pool drives the measured CK flux in the intact heart, and during isovolumic work, the CK reaction operates under saturating conditions; that is, the substrate concentrations are at least 2-fold greater than the K{sub m} or K{sub im} for each substrate. However, during KCl arrest the reaction does not operate under saturating conditions and the CK reaction velocity is strongly influenced by the guanidino substrate pool size.

• OSTI ID: 5026453
• Journal Information: Biochemistry; (United States), Vol. 30:10; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CORONARIES
FLOW RATE
PHOSPHOTRANSFERASES
NUCLEAR MAGNETIC RESONANCE
BIOCHEMICAL REACTION KINETICS
CREATINE
HEART
METABOLITES
PHOSPHORUS 31
RABBITS
AMINO ACIDS
ANIMALS
ARTERIES
BLOOD VESSELS
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
ENZYMES
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
REACTION KINETICS
RESONANCE
STABLE ISOTOPES
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques