IgG abzymes with peroxidase and oxidoreductase activities from the sera of healthy humans

Abstract

We present the evidence showing that small fractions of electrophoretically homogeneous immunoglobulin G (IgGs) from the sera of healthy humans and their Fab and F(ab)2 fragments oxidize 3,3'-diaminobenzidine through a peroxidase activity in the presence of H2 O2 and through an oxidoreductase activity in the absence of H2 O2 . During purification on protein G-Sepharose and gel filtration, the polyclonal IgGs partially lose the Me(2+) ions. After extensive dialysis of purified Abs against agents chelating metal ions, the relative peroxidase activity decreased dependently of IgG analyzed from 100 to ~10-85%, while oxidoreductase activity from 100 to 14-83%. Addition of external metal ions to dialyzed and non-dialyzed IgGs leads to a significant increase in their activity. Chromatography of the IgGs on Chelex non-charged with Cu(2+) ions results in the adsorption of a small IgG fraction bound with metal ions (~5%), while Chelex charged with Cu(2+) ions bind additionally ~38% of the total IgGs. Separation of Abs on both sorbents results in IgG separation to many different subfractions demonstrating various affinities to the chelating resin and different levels of the specific oxidoreductase and peroxidase activities. In the presence of external Cu(2+) ions, the specific peroxidase activity of several IgG subfractions achieves 20-27 % as compared with horseradish peroxidase (HRP, taken for 100%). The oxidoreductase activity of these fractions is ~4-6-fold higher than that for HRP. Antioxidant enzymes such as superoxide dismutases, catalases, and glutathione peroxidases are known to represent critical defence mechanisms for preventing oxidative modifications of DNA, proteins, and lipids. Peroxidase and oxidoreductase activities of human IgGs could also play an important role in the protection of organisms from oxidative stress and toxic compounds.

Immune System Dysregulation and Autoimmunity in Schizophrenia: IgGs from Sera of Patients with Several Catalytic Activities

“…Interestingly, the same activities were detected in IgG from the blood of healthy people [120,121]. The relative peroxidase activity of IgG of healthy people in the absence of external metal ions varies very much from donor to donor, but on average, it is about five times lower than in rat IgGs [120,121].…”

“…Оnly 17% of rat IgGs were shown to possess catalase activity. It was shown that small fractions of IgGs and their F(ab) 2 and Fab fragments of IgGs from sera healthy humans oxidize 3,3′-diaminobenzidine in the presence of H 2 O 2 through a peroxidase and in the absence of H 2 O 2 through an oxidoreductase activity [120,121].…”

“…It was shown that IgGs from the blood of healthy Wistar rats possess high H 2 O 2 -dependent peroxidase (hereinafter peroxidase) and H 2 O 2 -independent oxidoreductase (hereinafter oxidoreductase) activities in the oxidation of horseradish peroxidase substrate-3,3′-diaminobenzidine and some other aromatic amines, phenols, and quinones [135][136][137][138]. Interestingly, the same activities were detected in IgG from the blood of healthy people [120,121]. The relative peroxidase activity of IgG of healthy people in the absence of external metal ions varies very much from donor to donor, but on average, it is about five times lower than in rat IgGs [120,121].…”

Minor and Trace Elements in Whole Blood, Tissues, Proteins and Immunoglobulins of Mammals

“…From 26 to 39% of rat IgGs can interact with less or more efficiently with different metals ions. Interestingly, chromatography of IgGs from human plasmas on Chelex non-charged with metal ions led to the binding of a small amount of IgGs (~ 5%) bound with metal ions [36]. Chelex charged with Cu 2+ ions additionally adsorbed ~ 38% of the total IgGs.…”

“…It was demonstrated that small fractions of IgGs from the sera of healthy humans as well as their Fab and F(ab) 2 fragments oxidize DAB through peroxidase and oxidoreductase activities [36]. In contrast to rat antibodies, IgGs from human blood have both the dependent and independent on metal ions activities.…”