Reply to Richarme: Evidence against a role of DJ-1 in methylglyoxal detoxification [Letters to the Editor]

This is a response to a letter by Richarme (1).We thank Dr. Richarme for the opportunity to clarify the points raised in his letter. We address the points relating to our data in the order in which they are raised.In our paper (2), we find that Tris buffer alone is able to reproduce the drop in A290 described in Ref. 3, whereas neither Drosophila DJ-1β nor human DJ-1, when dialyzed into PBS, causes this drop in A290. Dr. Richarme points out that we did not specify the final concentration of Tris used in our assays. We set up our assay to be similar to the conditions described in Richarme et al. (3). According to the "Experimental Procedures" of this paper, "DJ-1 was purified as described previously (28)," and according to the "Experimental Procedures" of Ref. 28 (shown below as Ref. 4), the DJ-1 homolog, YajL, was "dialyzed for 2 h against 30 mm Tris, pH 8." Hence, in our initial assays, we dialyzed our DJ-1 proteins into 20 mm Tris, 150 mm NaCl, yielding a final concentration of 1 mm Tris in our deglycation assay. Thus, our final deglycation reaction assays are: 50 mm sodium phosphate buffer, pH 7.0, 2 mm methylglyoxal, 2 mm reduced glutathione or N-acetylcysteine, and either 4 μm DJ-1 or 1.0 mm Tris, pH 8.0. We provide here in Fig. 1A a titration curve of Tris in the deglycation assay, which shows that even 0.4 mm Tris can cause this drop.jbc;292/31/12784/F1F1F1Figure 1.Additional data supporting our original...

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