Development of super catalytic antibody and application to new biosensor

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1. Many antibody genes were analyzed and then the enzymatic activities of the subunits were investigated. As the consequence, a characteristic feature that the catalytically active antibodies have the unique structure like catalytic triad in their conformation was revealed. The three dimensional structures of 91 monoclonal antibodies were examined using PDB and ours data. Over 30% of the antibodies possess the catalytic triad-like structure in their conformation. This means that such gene as being able to construct the catalytic triad-like structure is inherently present in germ line. The peptidase or/and protease activity of the antibody was observed whenever such structure was confirmed in the conformation by the molecular modeling.2. We have found out some natural catalytic antibodies (the super catalytic antibody belongs to this category) for three years research program. The light and heavy chain of i41SL1-2 antibody displayed a short induction period and then high catalytically active phase started to decompose the antigen, resulting two phases reaction. These subunits of i41SL1-2 antibody showed similar behavior as a serine protease in the enzymatic reaction. Regarding the immunoaffinity to the antigen, they showed higher value than trypsin. On the other hand, with respect to kcat, the subunits displayed lower value in comparison with that of trypsin. Thus, the catalytic antibody is defined as a molecule situating between antibody and enzyme from the viewpoint of specificity and catalysis.3. A new sensing system was accomplished using the reaction between some ruthenium complexes and amino acid (or peptide) which could be detected with the sensitivity of around 10^<-6>/M