Strict criteria prove that the catalase activity is intrinsic properties of scz-IgG_mix and health-IgG_mix.

Preparations of scz-IgG_mix (A) and healthy-IgG_mix (B) were separated by FPLC gel filtration on a Superdex 200 column in an acidic buffer Gly-HCl pH 2.6 after Abs incubation in the same buffer: (—), absorbance at 280 nm (A₂₈₀); (○), relative activity (RA) of the IgG_mix in the degradation of H₂O₂. Analysis of the thermal stability of scz-IgG_mix; the preparation was preincubated at various temperatures for 10 minutes and then its relative catalytic activity was estimated using standard conditions (C). SDS-PAGE analysis of catalase activity of intact scz-IgG_mix (D) as well as separated H, L chains and their L_nH_n oligomers (F) in non-reducing SDS-PAGE gradient 4–15% scz-IgG_mix before (D) and after treatment of IgGs with DTT (F); panel F corresponds to lane 2 of Panel E. The relative catalase activity (RA, A₂₄₀/min) was revealed using the extracts of 2-3-mm many fragments of one longitudinal slice of the gel corresponding IgGs before (D) and after treatment with DTT (F). The control longitudinal slices of the same gels were stained with Coomassie R250 (E): lane 1 corresponds to intact IgG_mix, lane 2 to IgG_mix incubated with 40 mM DTT for 10 min at 30°C, lane 3 to IgG_mix boiled with DTT. Lane C (E) shows the positions of molecular mass standard markers. The relative activity of F(ab) and F(ab)₂ fragments of individual IgG(4), IgG(12), and IgG(14) (G). The average error of the initial rate determination from two experiments did not exceed 10–15%. For details, see Materials and methods.