| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2013: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2012: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2011: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Research Abstract |
To investigate the molecular basis of cold adaptation of enzymes, we determined the crystal structure of the tryptophan synthase alpha subunit from the psychrophile Shewanella frigidimarina K14-2 and also examined its physicochemical properties. The lower stabilities against heat and denaturant of the psychrophile enzyme originated from both a faster unfolding rate and a slower refolding rate. The two-state transition of denaturation for the enzyme was highly cooperative. Relative to tryptophan synthases from other species, the psychrophile enzyme exhibited an increase in cavity volume and a decrease in the number of ion pairs. The enzyme also lacks a hydrogen bond near a loop related to catalytic function. These characteristics of the psychrophile enzyme might provide the conformational flexibility required for catalytic activity at low temperatures.
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