Enzymes or redox couples? The kinetics of thioredoxin and glutaredoxin reactions in a systems biology context

Date
2009
Authors
Pillay C.S.
Hofmeyr J.-H.S.
Olivier B.G.
Snoep J.L.
Rohwer J.M.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Systems biology approaches, such as kinetic modelling, could provide valuable insights into how thioredoxins, glutaredoxins and peroxiredoxins (here collectively called redoxins), and the systems that reduce these molecules are regulated. However, it is not clear whether redoxins should be described as redox couples (with redox potentials) or as enzymes (with Michaelis-Menten parameters) in such approaches. We show that in complete redoxin systems, redoxin substrate saturation and other purported enzymatic behaviours result from limitations in the redoxin redox cycles in these systems. Michaelis-Menten parameters are therefore inappropriate descriptors of redoxin activity; data from redoxin kinetic experiments should rather be interpreted in terms of the complete system of reactions under study. These findings were confirmed by fitting kinetic models of the thioredoxin and glutaredoxin systems to in vitro datasets. This systems approach clarifies the inconsistencies with the descriptions of redoxins and emphasizes the roles of redoxin systems in redox regulation. © The Authors Journal compilation.
Description
Keywords
Glutathione, Kinetic modelling, NADPH, Redoxin, Reductase, Thiol, Catalysts, Enzymes, Enzyme activity, glutaredoxin, thioredoxin, article, controlled study, enzyme activity, enzyme kinetics, enzyme substrate, in vitro study, Michaelis Menten kinetics, oxidation reduction reaction, priority journal, systems biology, biological model, kinetics, metabolism, methodology, Glutaredoxins, Kinetics, Models, Biological, Oxidation-Reduction, Systems Biology, Thioredoxins
Citation
Biochemical Journal
417
1