Use of isotope effects to elucidate enzyme mechanisms
The chemical bond breaking steps are normally not rate limiting for enzymatic reactions. However, comparison of deuterium and tritium isotope effects on the same reaction, especially when coupled with /sup 13/C isotope effects for the same step measured with deuterated as well as unlabeled substrates, allows calculation of the intrinsic isotope effects on the bond breaking steps and thus a determination of the commitments to catalysis for the reactants. The variation in observed isotope effects as a function of reactant concentration can be used to determine kinetic mechanisms, while the pH variation of isotope effects can determine the stickiness of the reactants and which portions of the reactant mechanism are pH dependent. Finally the size of primary and secondary intrinsic isotope effects can be used to determine transition state structure.
- Research Organization:
- Department of Biochemistry, University of Wisconsin, Madison
- OSTI ID:
- 6258014
- Journal Information:
- CRC Crit. Rev. Biochem.; (United States), Journal Name: CRC Crit. Rev. Biochem.; (United States) Vol. 13:4; ISSN CRBCA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanism of the reaction catalyzed by dihydrofolate reductase from Escherichia coli: pH and deuterium isotope effects with NADPH as the variable substrate
Use of isotope effects as a probe of enzyme reaction mechanisms
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CALCULATION METHODS
CARBON 13
CARBON ISOTOPES
CATALYSIS
CHEMICAL BONDS
DEUTERIUM
ENZYME ACTIVITY
ENZYMES
EVEN-ODD NUCLEI
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MOLECULAR BIOLOGY
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PH VALUE
QUANTITY RATIO
RADIOISOTOPES
REACTION KINETICS
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
TRITIUM
YEARS LIVING RADIOISOTOPES