Response to Dr. Moskovitz

In our technical note entitled “Wanted and Wanting: Antibody Against Methionine Sulfoxide” [1], we pointed out several errors of fact and unsupportable interpretations of experimental observations that were included in a paper reporting attempts to raise a rabbit polyclonal antiserum specific for methionine sulfoxide [2]. The immunogen employed was a corn protein rich in methionine that had been exposed to hydrogen peroxide to convert many of the methionines to methionine sulfoxide. While we do not know the epitopes recognized by the antiserum, we certainly established that there is no specificity for methionine sulfoxide itself. Dr. Moskovitz, the senior author of that paper, now states in his Letter to the Editor that our conclusion of the lack of specificity “has no merit”. He cites several studies that employed the antiserum and found differences between control and experimental samples. He argues that these studies establish specificity. In fact, the cited studies do not report investigations of specificity; they assume that it is specific for methionine sulfoxide based on the claim made in Moskovitz and colleague’s original report [2]. As pointed out in our note, multiple investigators have failed to produce an antiserum or antibody specific for methionine sulfoxide. Both Dr. Moskovitz and we are members of that group of investigators.