Detection and localization of methionine sulfoxide residues of specific proteins in brain tissue.

Methionine sulfoxide is a common posttranslational oxidative modification that can alter protein function. Vulnerability of specific proteins to methionine oxidation varies and depends on their structure. In the current study, detection of methionine sulfoxide in intact proteins is mediated by novel anti-methionine sulfoxide antibody that resulted in the identification of three major methionine sulfoxide-proteins in brain: bisphosphate aldolase A and C, α and β subunits of hemoglobin, and serum albumin. The locations of the methionine sulfoxide residues were determined by massspectrometry analyses. It is suggested that the in vivo methionine oxidation of these proteins represent early posttranslational oxidative modification of proteins in brain. Thus, elevated levels of methionine-sulfoxide in these proteins may serve as bio-markers for enhanced oxidative stress in brain, which may be associated with brain disorders and diseases.