Effect of CoCl₂ on the content of different metals and a relative activity of DNA‐hydrolyzing abzymes in the blood plasma of mice

Abstract

Cobalt is a transition metal and an essential trace element that is required for vitamin B₁₂ biosynthesis, enzyme activation, and so on but is toxic in high concentrations. It was shown that the content of different elements in the plasma of 2-month-old BALB/c mice (control group) decreased in the following order: Ca > Mg > Si > Fe > Zn > Cu ≥ Al ≥ B. The treatment of mice with CoCl₂ did not appreciably change the relative content of Ca, Cu, and Zn, but a significant increase in the content of B (2.3-fold), Mg (1.5-fold), Al and Fe (2.1-fold), and Si (3.4-fold) was found. The treatment of mice led to a 2.2-fold decrease in the concentration of the total blood protein and a 1.7 ± 0.2-fold decrease of total immunoglobulin Gs (IgGs). Deoxyribonuclease IgGs corresponding to mice treated (t-IgGs) and non-treated (nt-IgGs) with CoCl₂ contained intrinsically bound metal ions; these IgGs hydrolyzed DNA with very low activity but were not active in the presence of ethylenediaminetetraacetic acid or after Ab dialysis against ethylenediaminetetraacetic acid. The average RAs of deoxyribonuclease nt-IgGs increased after addition of external metal ions in the following order: Zn²⁺< Ca²⁺ < Cu²⁺ < Fe²⁺ < Mn²⁺ < Mg²⁺ < Co²⁺ < Ni²⁺. Interestingly, t-IgGs demonstrated lower activities than those for nt-IgGs either in the absence of external metal ions (2.7-fold) or in the presence of Cu²⁺ (9.5-fold) > Co²⁺ (5.6-fold) > Zn²⁺ (5.1-fold) > Mg²⁺ (4.1-fold) > Ca²⁺ (3.0-fold) > Fe²⁺ (1.3-fold). However, the RAs of t-IgGs were remarkably more active than nt-IgGs in the presence of best activators of t-IgGs Ni²⁺ (1.4-fold) and especially Mn²⁺ (2.2-fold). The data may be useful for an understanding of Co toxicity, its effect on the concentration of other metal ions, and a change of metal-dependent specificity of Abzs.

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

“…But t-IgGs were more active than nt-IgGs in the presence of Ni 2+ (1.4-fold) and especially Mn 2+ (2.2-fold), which are the best activators of t-IgGs. These data may be useful for an understanding of Co 2+ toxicity, its effect on a change of metal-dependent specificity of mouse abzymes [30].…”

“…Transition-metal cobalt is an essential trace element required for vitamin B 12 biosynthesis, enzyme activation, etc., but is toxic in high concentrations. We estimated the effect of cobalt chloride (CoCl 2 ) on relative content of different metal ions in mouse plasma using TJP-AES and on the total protein content [29,30]. Freeze-dried plasma (2-3 mg) was available for the TJP-AES analysis.…”