Metal ions-dependent peroxidase and oxidoreductase activities of polyclonal IgGs from the sera of Wistar rats

✍ Scribed by Erdenechimeg N. Ikhmyangan; Nataliya L. Vasilenko; Valentina N. Buneva; Georgy A. Nevinsky

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 359 KB
• Volume: 19
• Category: Article
• ISSN: 0952-3499
• DOI: 10.1002/jmr.761

✦ Synopsis

We present evidence showing that a small fraction of electrophoretically homogeneous IgGs from the sera of healthy Wistar rats is bound with several different Me 2þ ions and oxidizes 3,3 0 -diaminobenzidine through a peroxidase activity in the presence of H 2 O 2 and through an oxidoreductase activity in the absence of H 2 O 2 . During purification on Protein A-Sepharose and gel filtration, the polyclonal IgGs partially lose the Me 2þ ions. Therefore, in the absence of external metal ions, the specific peroxidase activity of IgGs from the sera of different rats varied in the range 1.6-26% and increased up to 13-198% after addition of Fe 2þ or Cu 2þ ions as compared with horseradish peroxidase (HRP, taken for 100%). The oxidoreductase activity of HRP is 24-fold lower than its peroxidase activity, while oxidoreductase and peroxidase activities of IgGs are comparable. Oxidoreductase activities of different IgGs in the absence of external metal ions varied from 22 to 800%, and in the presence of Fe 2þ or Cu 2þ ions, from 37 to 1100% in comparison with the HRP oxidoreductase activity (100%). Chromatography of the IgGs on Chelex-100 leads to the adsorption of a small IgG fraction bound with metal ions and to its separation to many different subfractions demonstrating various affinities to the chelating resin and increased levels of the specific oxidoreductase and peroxidase activities. Antioxidant enzymes such as superoxide dismutases, catalases, and glutathione peroxidases are known to represent critical defense mechanisms for preventing oxidative modifications of DNA, proteins, and lipids. Peroxidase and oxidoreductase activity of antibodies may play an important role in the protection of organisms from oxidative stress and toxic compounds.