Systemic lupus erythematosus: Possible localization of trypsin‐like and metalloprotease active centers in the protein sequence of the monoclonal light chain (NGTA2‐Me‐pro‐Tr)

Abstract

It was previously shown that several monoclonal light chains corresponding to the phagemid library of recombinant peripheral blood lymphocyte immunoglobulin light chains of patients with systemic lupus erythematosus specifically hydrolyze only myelin basic protein (MBP). Canonical enzymes usually have only one active site catalyzing some kind of chemical reaction. It was shown previously that in contrast to classical enzymes, preparations of one of the light chains (NGTA2‐Me‐pro‐Tr) showed two optimal pH values, two optimal concentrations of metal ions, and two Km values for MBP. One protease active site of NGTA2‐Me‐pro‐Tr was trypsin like, whereas second one was metal dependent. In this article, a search for protein sequences of NGTA2‐Me‐pro‐Tr responsible for catalytic functions was carried out. We performed, for the first time, analysis of the homology of the protein sequence of NGTA2‐Me‐pro‐Tr with those of several classical Zn2+‐ and Ca2+‐dependent, as well as human serine, proteases. The analysis allowed us to identify the protein sequences of NGTA2‐Me‐pro‐Tr responsible for serine‐like activity, the binding of MBP, and chelation of metal ions and catalysis directly. The data obtained are summarized using hypothetical models of the structure of the two active centers of a very unusual light chain of antibodies (Abs). The findings obtained may be very important for understanding possible structure of active centers of very unusual light chain of Abs possessing several enzymatic activities.

Autoimmune Diseases: Enzymatic cross Recognition and Hydrolysis of H2B Histone, Myelin Basic Protein, and DNA by IgGs against These Antigens

“…From a theoretical point of view, the human immune system can create one antigen against about 10 5 –10 6 B-lymphocytes, which can produce Abs to the same antigen with different properties. This is in good agreement with our experimental data [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…The question concerning abzymes and their biological role is critical for understanding the mechanisms of many Ads’ development. To obtain monoclonal light chains with DNase and myelin basic protein (MBP)-hydrolyzing activities, the cDNA kappa library of light chains of peripheral blood antibodies of three SLE patients (10 6 variants of different light chains) and the phage display method were used [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. To obtain individual colonies corresponding to DNase IgGs, phage particles eluted from DNA cellulose with 0.5 M NaCl and acidic buffer (pH 2.6) were used [ 24 , 25 ].…”

“…These data unambiguously indicated that NGTA1-Me-pro has two metal-dependent active sites in one active center [ 27 ]. The sequence of NGTA1-Me-pro was shown to have a double set of protein sequences characteristic of the recognition sites of proteins, metal ions, and catalytic amino acid residues necessary for the hydrolysis of proteins in the case of several canonical metal proteases [ 30 ]. Specific inhibitors of NGTA2-Me-pro-Tr were PMSF (42%) and EDTA (58%): it exhibits the properties of a chimeric protease with serine and metal-dependent activities [ 31 ].…”

Essential Protective Role of Catalytically Active Antibodies (Abzymes) with Redox Antioxidant Functions in Animals and Humans

“…In addition, some anti-protein abzymes, such as against basic myelin proteins in MS and SLE patients, may be serine, thiol, or acid-type or metalloproteases [ 212 , 213 , 214 ]. However, there are abzymes in the active centers of which two active centers are combined, for example, serine and metalloproteases [ 215 ]. There are also antibodies, in which three activities are combined in the active centers—serine, metalloprotease, and DNase [ 216 ].…”

“…There are also antibodies, in which three activities are combined in the active centers—serine, metalloprotease, and DNase [ 216 ]. Moreover, the structure of these monoclonal antibodies and amino acid residues corresponding to two or three activities is very close to those for canonical enzymes with the same catalytic activities [ 215 , 216 ].…”