Abstract
It is known that human milk contains secretory immunoglobulines A (sIgA-abzymes) possessing affinity to mammalian DNA and capacity to cleave plasmid DNA. Regulation of DNA-hydrolyzing activity of those sIgA-abzymes is poorly studied. Here we investigate the effect of nucleoside triphosphates towards the DNase activity of sIgA-abzymes which were purified from human milk by a sequential chromatography on protein A-agarose, DEAE-Fractogel, and DNA-cellulose. By using DNA-hydrolysing assay, we revealed that 1 mM ATP and 1 mM dATP markedly reduced the cleavage of linear form of plasmid DNA by sIgA-abzymes, while the effect of GTP, CTP, TTP and dGTP was much weaker. dCTP and dTTP did not influence DNase activity of the sIgA-abzymes. Possible mechanisms of nucleotide-mediated inhibition of the DNase activity of sIgA-abzymes are discussed. Keywords: abzymes, secretory immunoglobulin A, human milk, DNA-hydrolyzing activity.
Highlights
DNA-hydrolyzing IgGs were originally discovered in blood serum of patients with the autoimmune disease – systemic lupus erythromatosis [1]
We show that ribo- and deoxyribonucleoside triphosphates inhibit DNA-hydrolyzing activity of sIgA-abzymes isolated from human milk, and that effect significantly depends on the nucleotide type
The 1st one is based on data showing that the catalytic center of sIgA-abzymes possessing DNase activity is located in the light chain, while the DNA-binding center is predominantly formed by its heavy chain [10]
Summary
DNA-hydrolyzing IgGs were originally discovered in blood serum of patients with the autoimmune disease – systemic lupus erythromatosis [1]. Antibodies possessing similar activity have been revealed in blood serum of patients with various types of autoimmune and with non-autoimmune diseases [2, 3]. Natural catalytic antibo dies which belong to sIgA and IgG classes have been found in woman’s colostrum and milk [2, 4]. Those abzymes possessed a capacity to phosphorylate proteins [5, 6], lipids [7, 8], and polysaccharides [9]. We show that ribo- and deoxyribonucleoside triphosphates inhibit DNA-hydrolyzing activity of sIgA-abzymes isolated from human milk, and that effect significantly depends on the nucleotide type
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