ABSTRACT
This chapter focuses on the steps of the catalytic cycle Glutathione peroxidases (GPx), having a closer look at the undisclosed chemistry at the quantum mechanics and the molecular dynamics level of theory. GPx are the members of a protein family which is widespread in the whole tree of life. The typical redox-sensitive spectral absorbance of their heme prosthetic group indeed made enzymological studies easy. The class of thiol peroxidases is split into GPx and peroxiredoxins. Both share the folding architecture known as thioredoxin fold, whose minimal information is given by a structural motif consisting of a central core of a four-stranded β-sheet and three surrounding α-helices. The basic shared mechanism of the reaction catalyzed is the reduction of hydroperoxides by thiols, where the redox transitions are faster than the formation of an enzyme–substrate complex and, consequently, KM and Vmax are infinite.
