Growth of High Quality Protein Crystals using Magnetic Field

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We chose hen egg-white lysozyme as a model protein, and studied a magnetic field effects on the crystallization of lysozyme crystals. Main results obtained are summarized as follows.1. Magnetic orientation of the crystalsMagnetic orientation of protein crystals could be controlled by changing the growth rate and depth of the crystallization container in addition to the magnetic field strength.2. Growth rate of the crystalsIn situ observation of growing protein crystals under 11T revealed that a magnetic field decreased the growth rate of the crystals.3. Damping of convection in NaCl aqueous solutionIn situ observation of temperature-driven convection in NaCl aqueous solution showed that a magnetic field damped the convection even in the case of "aqueous solution".4. Improvement of the quality of the crystalRocking curve measurement of orthorhombic lysozyme crystals grown under 10T revealed that a magnetic field drastically increased the "crystal perfection" of protein single crystal., and gave higher diffraction limit and smaller X-ray radiation damage.5. Effects of other external force I : high pressureWith an increase in hydrostatic pressure, solubility of tetragonal lysozyme crystals increased, though that of orthorhombic one decreased. Increase in surface energy decreased the growth rate of tetragonal and orthorhombic crystals.6. Effects of other external force II : microgravityMicrogravity experiments using dropping facility revealed that 1) Grashoff number could be a good measure to predict buoyancy convection, and that 2) Marangoni convection at water-air interface decreased to less than 10% within 10-15 min because of the contamination of the interface.