Correlation between biological activity and electron transferring of bovine liver catalase: Osmolytes effects

Abstract

• Proline increases ET in Bovine Liver Catalase (BLC) whereas histidine decreases it. • Proline also increased the biological activity, whereas histidine decreased it. • Electron transferring and biological activity for BLC are directly correlated. • Proline causes favorable ET for BLC shown by positive E 1/2 ( E °′) and negative Δ G . • Histidine makes ET unfavorable for BLC, manifested by E 1/2 ( E °′) < 0 and Δ G > 0. Catalase is a crucial antioxidant enzyme that protects life against detrimental effects of H 2 O 2 by disproportionating it into water and molecular oxygen. Effect of proline as a compatible and histidine as a non compatible osmolyte on the electron transferring and midpoint potential of catalase has been investigated. Proline increases the midpoint potential (Δ E m > 0), therefore causing the Δ G ET to be less positive and making the electron transfer reaction more facile whereas histidine decreases the E m (Δ E m < 0) and consequently a causes a pronounced increase in Δ G ET , thereby rendering the electron transfer reaction less efficient. These results indicate the inhibitory effect of histidine evident by a −37% decrease in the cathodic peak current compared to 16% increase in the case of proline indicative of activation. The insight paves the tedious way towards our ultimate goal of elucidating a correlation between biological activity and electron transferring.