Metal-catalyzed oxidation of alpha-synuclein in the presence of Copper(II) and hydrogen peroxide.
alpha-Synuclein is a component of abnormal protein depositions of Lewy bodies and senile plaques found in Parkinson's and Alzheimer's diseases, respectively. By using chemical coupling reagents such as dicyclohexylcarbodiimide or N-(ethoxycarbonyl)-2-ethoxy-1, 2-dihydroquinoline, the protein was shown to experience self-oligomerization in the presence of either copper(II) or Abeta25-35. The oligomers which appeared as a ladder on a 10-20% Tricine/SDS-PAGE have been suggested to participate in the formation of protein aggregations by possibly providing a nucleation center. Since oxidatively modified protein could increase its own tendency toward protein aggregation, metal-catalyzed oxidation of alpha-synuclein has been examined with copper(II) and hydrogen peroxide in the absence of the coupling reagent. Intriguingly, the protein was also self-oligomerized into an SDS-resistant ladder on the gel. This biochemically specific copper-mediated oxidative oligomerization was shown to be dependent upon the acidic C-terminus of alpha-synuclein because the C-terminally truncated proteins such as alpha-syn114 and alpha-syn97 were not affected by the metal and hydrogen peroxide. More importantly, the oxidative oligomerization was synergistically enhanced by the presence of Abeta25-35, indicating that the peptide interaction with alpha-synuclein facilitated the copper(II) binding to the acidic C-terminus and subsequent oxidative crosslinking. It has been, therefore, suggested that abnormalities in copper and H(2)O(2) homeostasis and certain pathological factors functionally similar to the Abeta25-35 could play critical roles in the metal-catalyzed oxidative oligomerization of alpha-synuclein, which may lead to possible protein aggregation and neurodegenerations.
Paik
S R
SR
Department of Biochemistry, College of Medicine, Inha University, 253 Yonghyun-Dong, Inchon, 402-751, Korea. sraik@dragon.inha.ac.kr
Shin
H J
HJ
Lee
J H
JH
D000477:Alkylating Agents / Q000494:pharmacology; D000544:Alzheimer Disease / Q000378:metabolism; D002384:Catalysis; D002712:Chlorides; D003300:Copper / Q000378:metabolism*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005290:Ferric Compounds / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D011804:Quinolines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D051843:Synucleins; D013997:Time Factors; D051844:alpha-Synuclein
D000477:Alkylating Agents; D002712:Chlorides; D005290:Ferric Compounds; D008670:Metals; D009419:Nerve Tissue Proteins; D011804:Quinolines; D011994:Recombinant Proteins; C497604:SNCA protein, human; D051843:Synucleins; D051844:alpha-Synuclein; D004024:Dicyclohexylcarbodiimide; C000470:EEDQ; D003300:Copper; D006861:Hydrogen Peroxide; C029892:cupric chloride; C024555:ferric chloride