Our recent studies revealed the successful identifications of three lysins in the catalytic site and two lysins in the regulatory site in the spinach RuBisCO by the use of specific chemical modification method.
　In this study, the introduction of lysins of plant RuBisCO into the bacteria RuBisCO has been examined. A new mutant RuBisCO has been obtained by introducing two lysins among three of plant RuBisCO into the bacteria one. The enzymatic characteristics have been investigated on the new RuBisCO．The results show the different behavior in enzymatic activity from the original bacteria RuBisCO. The elevation of activity is　significantly large as the 40％ increase in κcat.
　The structural studies has also been proceeded to get a clear evidence about the regulatory site of enzymatic activity. Two forms of single crystals were obtained from the hanging drop vapor diffusion method using polyethylene glycol as a precipitant. Diffraction intensities from one of the crystals were measured and treated for structure determination. Now the refinement of the crystal structure is reached to the 2.5Å resolution.