Abstract
Kinetic isotope effects on enzyme catalyzed reactions are indicative for the first irreversible in a sequence of individual steps. Hints on the relative velocities of other steps can only be obtained from the partitioning factor R and its dependence on external reaction conditions. In general, the experimental data needed are obtained from isotope abundance measurements in a defined position of the substrate or product as a function of turnover. This method does not reveal events dealing with neighbour atoms or preceding the main isotope sensitive step. In the method presented here, the analytical measurement is extended to the second atom involved in a bond fission of formation (Double Isotope Effect Method). It is shown that the additional results obtained support the identification of the main isotopically sensitive step and its relative contribution to the overall reaction rate, the identification of other kinetically significant steps and the differentiation between stepwise and concerted reaction mechanisms. The method and its advantages are demonstrated on reactions comprising C-N-bond splitting (urease and arginase reaction), C-C-bound fission (reactions catalyzed by pyruvate-dehydrogenase, pyruvate-formiate-lyase and lactate-oxidase), C-O-bound formation (ribulose-bisphosphate-oxygenase reaction), and N-O-bond fission (nitrate- and nitrite-reductase reactions). (orig.).
Schmidt, H L;
Medina, R
[1]
- Technische Univ. Muenchen, Freising (Germany, F.R.). Lehrstuhl fuer Allgemeine Chemie und Biochemie
Citation Formats
Schmidt, H L, and Medina, R.
Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions.
Germany: N. p.,
1991.
Web.
Schmidt, H L, & Medina, R.
Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions.
Germany.
Schmidt, H L, and Medina, R.
1991.
"Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions."
Germany.
@misc{etde_5556011,
title = {Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions}
author = {Schmidt, H L, and Medina, R}
abstractNote = {Kinetic isotope effects on enzyme catalyzed reactions are indicative for the first irreversible in a sequence of individual steps. Hints on the relative velocities of other steps can only be obtained from the partitioning factor R and its dependence on external reaction conditions. In general, the experimental data needed are obtained from isotope abundance measurements in a defined position of the substrate or product as a function of turnover. This method does not reveal events dealing with neighbour atoms or preceding the main isotope sensitive step. In the method presented here, the analytical measurement is extended to the second atom involved in a bond fission of formation (Double Isotope Effect Method). It is shown that the additional results obtained support the identification of the main isotopically sensitive step and its relative contribution to the overall reaction rate, the identification of other kinetically significant steps and the differentiation between stepwise and concerted reaction mechanisms. The method and its advantages are demonstrated on reactions comprising C-N-bond splitting (urease and arginase reaction), C-C-bound fission (reactions catalyzed by pyruvate-dehydrogenase, pyruvate-formiate-lyase and lactate-oxidase), C-O-bound formation (ribulose-bisphosphate-oxygenase reaction), and N-O-bond fission (nitrate- and nitrite-reductase reactions). (orig.).}
journal = []
volume = {27:1}
journal type = {AC}
place = {Germany}
year = {1991}
month = {Jan}
}
title = {Possibilities and scope of the double isotope effect method in the elucidation of mechanisms of enzyme catalyzed reactions}
author = {Schmidt, H L, and Medina, R}
abstractNote = {Kinetic isotope effects on enzyme catalyzed reactions are indicative for the first irreversible in a sequence of individual steps. Hints on the relative velocities of other steps can only be obtained from the partitioning factor R and its dependence on external reaction conditions. In general, the experimental data needed are obtained from isotope abundance measurements in a defined position of the substrate or product as a function of turnover. This method does not reveal events dealing with neighbour atoms or preceding the main isotope sensitive step. In the method presented here, the analytical measurement is extended to the second atom involved in a bond fission of formation (Double Isotope Effect Method). It is shown that the additional results obtained support the identification of the main isotopically sensitive step and its relative contribution to the overall reaction rate, the identification of other kinetically significant steps and the differentiation between stepwise and concerted reaction mechanisms. The method and its advantages are demonstrated on reactions comprising C-N-bond splitting (urease and arginase reaction), C-C-bound fission (reactions catalyzed by pyruvate-dehydrogenase, pyruvate-formiate-lyase and lactate-oxidase), C-O-bound formation (ribulose-bisphosphate-oxygenase reaction), and N-O-bond fission (nitrate- and nitrite-reductase reactions). (orig.).}
journal = []
volume = {27:1}
journal type = {AC}
place = {Germany}
year = {1991}
month = {Jan}
}