Figure 4. Formation of Hsp90 protein radicals following oxidative stress.

(A) Immuno-spin trapping blots showing the formation of nitrone adducts in Hsp90α (200 µg) incubated with DMPO (1 mM) and exposed to oxidative stress generated by Glox (60 mM glucose/1 U/ml glucose oxidase) supplemented with ADP (0.2 mM) and FeCl₃ (0.5 mM). Blank and Ctrl mean, respectively, that DMPO and Glox were omitted. (B) Same as (A) but with Hsp90β. (C) Proposed mechanism leading to oxidative polypeptide cleavage according to Stadman et al [18], [19].