Time-transient process of magnetically induced growth of nematic domains in a biological macromolecular liquid crystal

Hirai, Mitsuhiro; Takizawa, Toshiharu; Yabuki, Sadato; Hirai, Toshihiro; Ueki, Tatzuo; Sano, You

doi:10.1103/physreve.51.1263

Cited by 11 publications

(3 citation statements)

References 29 publications

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“…These anisotropies at all positions were much clearly seen compared to the case of the 30 mg/ml suspension. As shown previously (Hirai et al, 1995(Hirai et al, , 1997, in nematic phase TMV particles form nematic microdomains where TMV particles are pointing by preference along the nematic domain directors. Thus, in the present case, Fig.…”

Section: Figuresupporting

confidence: 70%

“…TMV is known to take a well-defined isomorphous cylindrical structure of ~180 Å in diameter and ~3000 Å in height (Namba et al, 1989), therefore TMV suspensions are regarded as an ideal model system of hard spherocylinders whose phase behavior is an attractive scientific concern relating to cooperative phenomena in liquid crystal phase transitions. We determined the phase diagram of TMV suspension on magnetic field strength and molecular concentration, and clarified the mechanism of orientational relaxation of TMV particles (Hirai et al, 1995(Hirai et al, , 1997.…”

Section: Introductionmentioning

confidence: 99%

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Right- / left-circular orientation of biological macromolecules under magnetic field gradient

Hirai¹,

Koizumi²,

Han³

et al. 2003

J Appl Cryst

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In spite of many studies on phase behaviors and orientational phenomena of biological marcomolecular suspensions under magnetic field, a translational force from magnetic field gradient was paid less attention. We have developed a high-performance compact magnetic circuit that can apply both periodic magnetic field strength and gradient to samples. Owing to the periodicity of the magnetic field strength and gradient, macromolecules are subject to both rotational and translational forces from magnetic field. By using this magnet, we have carried out time-resolved small-angle X-ray scattering measurements on an orientational behavior of a biological supermolecular suspension under periodic magnetic field and gradient. The sample was tobacco mosaic virus (TMV) which is one of rod-shaped plant viruses. The time courses of the orientational processes of TMV were monitored by a two-dimensional CCD detector. We have found that right-circular or left-circular orientation of TMV appears depending on a combination of magnetic field and gradient directions. Such a translational force from magnetic field gradient is able to cause various interesting phenomena of macromolecular systems, which would be applicable to a control of nano-scale assembling processes of macromolecules.

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Section: Figuresupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Right- / left-circular orientation of biological macromolecules under magnetic field gradient

Hirai¹,

Koizumi²,

Han³

et al. 2003

J Appl Cryst

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“…In the present case the broad peak at q Ϸ 0.07 Å Ϫ1 is evidently attributable to the interparticle correlation under repulsive Coulomb potential, whose width and height depend on the effective charge of the protein surface (Hirai et al, 1996a). Except for a highly concentrated system composed of large anisotropic-shaped particles forming liquid crystal ordering (Hirai et al, 1995(Hirai et al, , 1997, for globular particle systems in solutions the repulsive interaction between the particles usually produces only a broad single peak at the small q region owing to a large thermal energy of Brownian motion, which scarcely affects the scattering curve in the q region above the peak position FIGURE 1 Concentration dependence of the scattering curve I(q) of the HEWL solution in 50 mM Hepes buffer at 25°C. The concentration was varied from 0.5% w/v to 20% w/v.…”

Section: Resultsmentioning

confidence: 53%

Reversibility and Hierarchy of Thermal Transition of Hen Egg-White Lysozyme Studied by Small-Angle X-Ray Scattering

Arai

Hirai

1999

Biophysical Journal

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To clarify mechanisms of folding and unfolding of proteins, many studies of thermal denaturation of proteins have been carried out at low protein concentrations because in many cases thermal denaturation accompanies a great tendency of aggregation. As small-angle x-ray scattering (SAXS) measurements are liable to use low-concentration solutions of proteins to avoid aggregation, SAXS has been regarded as very difficult to observe detailed features of thermal structural transitions such as intramolecular structural changes. By using synchrotron radiation SAXS, we have found that the presence of repulsive interparticle interaction between proteins can maintain solute particles separately to prevent further aggregation in thermal denaturation processes and that under such conditions the thermal structural transition of hen egg-white lysozyme (HEWL) holds high reversibility even at 5% w/v HEWL below pH approximately 5. Because of the use of the high concentration of the solutions, the scattering data has enough high-statistical accuracy to discuss the thermal structural transition depending on the structural hierarchy. Thus, the tertiary structural change of HEWL starts from mostly the onset temperature determined by the differential scanning calorimetry measurement, which accompanies a large heat absorption, whereas the intramolecular structural change, corresponding to the interdomain correlation and polypeptide chain arrangement, starts much prior to the above main transition. The present finding of the reversible thermal structural transitions at the high protein concentration is expected to enable us to analyze multiplicity of folding and unfolding processes of proteins in thermal structural transitions.

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Effects of a magnetic field on the nucleation and growth of protein crystals

Sazaki

Yoshida

Komatsu

et al. 1997

Journal of Crystal Growth

177

106

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Time-transient process of magnetically induced growth of nematic domains in a biological macromolecular liquid crystal

Cited by 11 publications

References 29 publications

Right- / left-circular orientation of biological macromolecules under magnetic field gradient

Right- / left-circular orientation of biological macromolecules under magnetic field gradient

Reversibility and Hierarchy of Thermal Transition of Hen Egg-White Lysozyme Studied by Small-Angle X-Ray Scattering

Effects of a magnetic field on the nucleation and growth of protein crystals

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