Abstract
In contrast to canonical proteases, myelin basic protein (MBP)-Sepharose-purified IgG from multiple sclerosis (MS) and systemic lupus erythematosus (SLE) patients efficiently hydrolyze only MBP, but not many other tested proteins. It was shown that anti-MBP SLE IgGs cleave nonspecific tri- and tetrapeptides with an extremely low efficiency and cannot efficiently hydrolyse longer oligopeptides corresponding to antigenic determinants (AGDs) of HIV-1 integrase. To identify all sites of IgG-mediated proteolysis corresponding to two AGDs of MBP, we have used a combination of reverse-phase chromatography (RPhC), MALDI spectrometry, and TLC to analyze the cleavage products of two (17- and 19-mer) encephalytogenic oligopeptides corresponding to these AGDs. Both oligopeptides contained several clustered major and minor sites of cleavage. The active sites of anti-MBP abzymes are localized on their light chains, while the heavy chains are responsible for the affinity of protein substrates. Interactions of intact globular proteins with both light and heavy chains of abzymes provide high specificity of MBP hydrolysis. The affinity of anti-MBP abzymes for intact MBP was ∼103-fold higher than for the oligopeptides. The data suggest that both oligopeptides interact mainly with the light chain of different monoclonal abzymes of total pool of IgGs, which possesses lower affinity for substrates, and therefore, depending on the oligopeptide sequences, their hydrolysis may be less specific.
Highlights
It is known, that the occurrence of auto-Abs in increased concentration is a distinctive feature of various autoimmune diseases (ADs)
To exclude possible artefacts due to traces of contaminating proteases, these fractions were separated by SDSPAGE and their proteolytic activity was detected after the extraction of proteins from the excised gel slices as in [9]; only sle-IgGmix and ms-IgGmix preparations were active, when hdIgGmix was catalytically inactive
To [9] it was shown that, in contrast to canonical proteases, the systemic lupus erythematosus (SLE) and Multiple sclerosis (MS) IgGmix purified on myelin basic protein (MBP)-Sepharose hydrolyzed only MBP but not many other tested proteins
Summary
That the occurrence of auto-Abs in increased concentration is a distinctive feature of various autoimmune diseases (ADs) (reviewed in [1,2,3,4,5,6,7,8]). Active artificial antibodies (Abs) or abzymes (Abzs) against transition chemical states of different reactions were studied intensively (reviewed in [1]). Healthy humans and patients with many diseases with insignificant autoimmune reactions usually lack abzymes or develop Abzs with very low catalytic activities, with these activities being often on a borderline of the sensitivity of detection methods (reviewed in [2,3,4,5,6,7,8]). Natural abzymes hydrolyzing DNA, RNA, polysaccharides, oligopeptides (OPs), and proteins are described from the sera of patients with several autoimmune (systemic lupus erythematosus, Hashimoto’s thyroiditis, polyarthritis, multiple sclerosis, asthma, rheumatoid arthritis, etc.) and viral diseases with a pronounced immune system disturbance (viral hepatitis, AIDS, and tick-borne encephalitis) (reviewed in [2,3,4,5,6,7,8,9,10]). Abzymes may play a significant positive and/ or negative role in broadening Ab properties, forming specific pathogenic patterns and clinical settings in different autoimmune conditions [1,2,3,4,5,6,7,8,9,10]
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