| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2012: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2011: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Outline of Final Research Achievements |
Genome sequencing of extremely halophilic archaeon Halobacterium salinarum NRC-1 was completed, and a chitinase-homolog (ChiN1) was found. The gene encoding ChiN1 was expressed in extremely halophilic archaeon Haloarcula japonica. The recombinant ChiN1 was most active at 1.0 M NaCl. Supercritical carbon dioxide (scCO2) is attracting as an environmentally friendly solvent since CO2 is an abundant resource. The scCO2 has been used as a solvent for enzyme-catalyzed organic synthesis. However, many enzymes are unstable in scCO2. In this study, some ChiN1 mutants with less lysines on its protein surface were prepared and characterized to find a category of enzymes with high tolerance toward CO2 pressurization. On the basis of the 3D structure model of ChiN1, more solvent-accessible lysines were replaced by alanines. The Ha. japonica-produced mutants were prepared and assayed for chitinase activity in scCO2. Two mutants showed higher activity than wild-type ChiN1 in 10 MPa scCO2 for 1 h.
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