| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
We had already obtained the following result concerning to the volumetric behavior of the typical and classical molten globule of bovine α-lactalbumin : although the volume of α-lactalbumin decreased during the conformational change ftom native to molten-globule (ΔV【approximately equal】 - 60 cm^3/mol)s, that from molten-globule to fully-unfolded state was nearly 0 cm^3/mol (Kobashigawa et al., Protein Sci., 8, 2765-2772(1999)). In the case of egg-white lysozyme, which does not show stable molten-globule and unfolds and refolds with two-state mechanism, the unfolding behavior under the pressure up to 100 Mpa cannot be explained with two-state mechanism, especially at lower temperature (0 〜 20℃). It suggests that the volumetric behavior is somewhat complicated. The molten globule of hen egg-white lysozyme is stabilized under pressure. Canine milk lysozyme shows extremely stable molten globule. The thermal behavior of canine milk lysozyme was investigated with differential scanning calorimetry and it is shown that the conformational changes from native to molten-globule and molten-globule to unfolded state are clearly separated to each other. This is because that the molten-globule state of canine milk lysozyme is extremely stable as compared to those of α-lactalbumins and conventional lysozymes. From mutational investigation, this stability is originated from the formation of hydrophobic cluster of His21, Ile56, Ala93 and Val109 in molten-globule state. As the origin of the stability is hydrophobic interaction, the volume is anticipated to increase during the conformational change from molten-globule to unfolded state. However, we have not yet proved it experimentally due to the lack of stability of the instrument under higher temperatures.
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