Residual EDTA bound by lens crystallins accounts for their reported resistance to copper-catalyzed oxidative damage.
It was recently reported that the structural proteins of the lens, the crystallins, possess unusual resistance to oxidative damage from a copper-catalyzed Fenton system. Data presented here demonstrate that this phenomenon is specific to copper-catalyzed systems and is not observed when iron is the metal catalyst. Further investigation has revealed that the apparent resistance to copper-catalyzed oxidation results from the presence of residual EDTA associated with the proteins. EDTA chelates the copper, inactivating it as a redox catalyst. This binding of EDTA to crystallins (or other proteins) occurs when the proteins present in EDTA-containing buffers are dialyzed directly against deionized water. Partial characterization of the association between EDTA and proteins is presented and its potential significance as a confounding factor in studies of the effects of metal-catalyzed oxidation on proteins is discussed.
Cui
X L
XL
Laboratory of Mechanisms of Ocular Diseases, National Eye Institute, Bethesda, Maryland 20892.
Qin
C
C
Zigler
J S
JS
D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000187:drug effects; D000818:Animals; D002417:Cattle; D003300:Copper / Q000494:pharmacology / Q000633:toxicity*; D019327:Copper Sulfate; D003459:Crystallins / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D004492:Edetic Acid / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron; D007908:Lens, Crystalline / Q000187:drug effects; D010084:Oxidation-Reduction; D012710:Serum Albumin, Bovine / Q000187:drug effects; D014020:Tissue Extracts
D003459:Crystallins; C045076:Fenton's reagent; D014020:Tissue Extracts; D012710:Serum Albumin, Bovine; D003300:Copper; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D000426:Alcohol Dehydrogenase; D019327:Copper Sulfate