24] Reversible oxidation of HIV-2 protease

Abstract

Publisher Summary The enzyme HIV-2 protease contains two conserved methionine residues. Although methionine is generally not considered a conservative substitute for cysteine, both amino acids are susceptible to oxidative modification and, therefore, inhibit the HIV-2 protease following oxidation. Methionines become oxidized in a variety of proteins and, for some proteins; oxidation can be reversed in vitro following treatment of the peptide with methionine sulfoxide reductase (MsrA). MsrA has been implicated in the repair of oxidative damage to various proteins, and studies involving a MsrA mutant in yeast cells indicate that this enzyme functions to reverse the oxidative damage that occurs following oxidative stress in vivo. These studies suggest a potential for regulation of protein function by reversible methionine oxidation. This chapter describes methods developed to specifically oxidize the methionine residues of HIV-2 protease and examine the effect on HIV-2 protease activity. In addition, there are techniques to partially reverse this process in vitro, thus restoring HIV-2 protease activity. This chapter describes these techniques and highlights the effects of reversible methionine oxidation on HIV-2 function.