The Water Effect on the Kinetics of the Bovine Liver Catalase

Flavio      Augusto Vicente Seixas; Milene      Ribeiro da Silva; Mario      Tyago Murakami; Priscilla      Tosqui; Marcio      Francisco Colombo

doi:10.2174/092986611796011392

Abstract

Catalase is an enzyme that occurs in almost all aerobic organisms. Its main metabolic function is to prevent oxidative damage to tissues induced by hydrogen peroxide which is a strong oxidizing agent. Catalase is very effective in performing this task, since it has the highest turnover rate among all the enzymes. The properties of catalase have been investigated extensively for many years; however, the role of the solvent molecules in the catalytic reaction of this enzyme has not yet been investigated. Therefore, the objective of this work was to investigate the contribution of the solvent molecules on the catalytic reaction of bovine liver catalase with its substrate H2O2 by the osmotic stress method. As a probe for protein structural changes in solution, the differential number of water molecules released during the transition from free to bound form of the enzyme was measured. These assays were correlated with protein structural data provided by the SAXS technique and crystallographic structures of free and CN?? bonded enzymes. The results showed that the difference in surface accessible area of the crystal structures does not reflect the variation that is observed in solution. Moreover, catalase is not influenced by the solvent during the catalytic reaction, which represents a lower energy barrier to be crossed in the overall energetics of the reaction, a fact that contributes to the high turnover rate of catalase.

Keywords: Catalase, osmotic stress method, enzyme kinetics, water effect, protein allostery, bovine liver catalase, SAXS technique, oxoferryl species, Mickaelis-Menten cons, Wyman linkage equation, Protein Data Bank, superimposition, quaternary structure, Oligomerization, catalytic reaction, Gibbs-Duhem expression, osmotic stress, thermodynamic parameters, MARCCD detector, Helico bacter pilory catalaseCatalase, osmotic stress method, enzyme kinetics, water effect, protein allostery, bovine liver catalase, SAXS technique, oxoferryl species, Mickaelis-Menten cons, Wyman linkage equation, Protein Data Bank, superimposition, quaternary structure, Oligomerization, catalytic reaction, Gibbs-Duhem expression, osmotic stress, thermodynamic parameters, MARCCD detector, Helico bacter pilory catalase