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The interaction between a single-chain Fv (sFv) of the monoclonal antibody 3A21 and its antigen, bovine pancreatic ribonuclease A (RNase A), was studied by site-directed mutagenesis of the hypervariable regions and fluorescence polarization analysis. The affinity constants of wild-type sFv and a mutant sFv D31A (Asp31 of heavy chain was replaced by Ala) for RNase A were found to be 2.7 x 10(7) and 4.7 x 10(6) M-1 in PBS at pH 7.2 and 37 degrees C, respectively. While the affinity constant of D31A is not affected by NaCl concentration, that of wild-type sFv is almost the same as that of D31A in the presence of more than 1 M NaCl. These results demonstrate that Asp31 of the heavy chain interacts electrostatically with a positively charged amino acid residue of RNase A.

The Kansai Electric Power Company has been engaged in the ongoing development of the redox flow battery (RFB) since 1985 in collaboration with Sumitomo Electric Industries, Ltd. The fundamentals and performance of RFB have been verified through field test projects such as the prototype 450 kW 2 h system and the advanced design 168 kW 8 h system installed in Tatsumi substation. Now RFB has total energy efficiency of more than 70% including inverter loss, etc., and RFB has been applied to a number of practical uses. Several RFB systems have been installed in a semiconductor factory (3000 kW for UPS), a university (500 kW for load leveling), and other locations.