高圧力の科学と技術
Online ISSN : 1348-1940
Print ISSN : 0917-639X
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17 巻 , 1 号
- Proteins and Pressure -
選択された号の論文の8件中1~8を表示しています
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特集 ―蛋白質と圧力―
  • 寺嶋 正秀, 木村 佳文, 星原 悠司
    17 巻 (2007) 1 号 p. 4-12
    公開日: 2007/04/12
    ジャーナル フリー
    In this article, reaction volumes and pressure effects on protein reactions are discussed by means of the pulsed laser induced transient grating (TG) spectroscopy. By the TG method, temporal profile of the protein reaction volume has been determined for the non-reversible reaction process. For examples, TG studies on the photo-chemical process of carboxymyoglobin and photoactive yellow protein are introduced. The reaction volume for each process has been determined, which can not be studied by the other spectroscopic methods such as transient absorption method. A high pressure optical system, which enabled us to measure the pressure dependence of the reaction volume, has also been reported.
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  • 石森 浩一郎
    17 巻 (2007) 1 号 p. 13-22
    公開日: 2007/04/12
    ジャーナル フリー
    By using spectroscopies under high pressure, we determined the volume changes associated with protein folding of reduced cytochrome c from the unfolded state to the native state. The pressure dependence of the equilibrium constant for the denaturation and the folding rate revealed that the volume change for the protein folding and the activation volume for the native state are negative. Such negative volumes can be accounted for by a decrease in volume resulting from the dehydration of hydrophobic groups, primarily the heme group, and the dehydration is mainly induced in the formation of the transition for the native state. We, therefore, propose that dehydration can compensate for the decreased entropy in the formation of protein structures, entropically promoting the protein folding reactions.
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  • 今井 隆志
    17 巻 (2007) 1 号 p. 23-31
    公開日: 2007/04/12
    ジャーナル フリー
    The partial molar volume (PMV) is the most fundamental thermodynamic quantity in considering the pressure effects on protein stability and function. The PMV is determined by the hydration as well as the geometry of the solute. However, it is difficult to extract the hydration effects from the PMV by the conventional methods. The 3D-RISM theory, which is a modern statistical-mechanical theory of molecular solvation, enables us to analyze the PMV in terms of hydration. In this article, recent applications of the 3D-RISM theory to some subjects concerning the PMV of protein are reviewed. The topics include the volume difference between low- and high-pressure structures, the volume change associated with the helix-coil transition, and the volume change accompanying ligand-protein binding.
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  • 北原 亮, 赤坂 一之
    17 巻 (2007) 1 号 p. 32-41
    公開日: 2007/04/12
    ジャーナル フリー
    Protein structure in solution fluctuates over a wide range of conformation, but the reality of the fluctuation has been little explored. In this article, we present an approach to this problem using variable pressure NMR spectroscopy. The method enables us to explore protein conformation over a wide range of conformational space than hitherto explored by conventional NMR method and brings about a new dynamic view on protein structure. The highlight of the method is the determination of the structural coordinates of semi-stable higher energy conformers that exist in low population in dynamic equilibrium with the stable "native" conformer under physiological conditions. Available evidence suggests that such high energy conformers play crucial roles in function in many proteins.
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  • 茶谷 絵理, 後藤 祐児
    17 巻 (2007) 1 号 p. 42-49
    公開日: 2007/04/12
    ジャーナル フリー
    Pressure is an important perturbant applied in studies of folding and unfolding of globular proteins. Recently, the application of this perturbant has been extended to the study of amyloid fibrils, which will be reviewed here. The effects of pressure on amyloid fibrils seem various, being positive or negative, dependent on the protein species and experimental conditions. Several reports have shown that pressure drives the formation of amyloid fibrils via pressure-induced unfolded structure of proteins. In contrast, there are also several studies showing the pressure-induced depolymerization of amyloid fibrils, suggesting the deficient packing and/or hydration in the fibril structure. Furthermore, a novel adaptation or maturation phenomenon has been found under pressurized conditions, demonstrating the structural diversity of amyloid fibrils, one of unique features which cannot be predicted with Anfinsen's dogma.
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  • 鈴木 良尚, 佐崎 元, 松本 雅光, 永澤 眞, 中嶋 一雄, 田村 勝弘
    17 巻 (2007) 1 号 p. 50-56
    公開日: 2007/04/12
    ジャーナル フリー
    Velocities of elementary steps and two-dimensional nucleation rates on the {101} face of glucose isomerase (GI) crystals were measured at pressures of 0.1, 25 and 50 MPa. We conducted in situ observation of the steps by using a laser confocal microscope combined with differential interference contrast microscope (LCM-DIM) and high-pressure vessel with a sapphire window (t = 1 mm). Both step velocities and 2D nucleation rates increased with increasing pressure at T = 26.4°C and C = 5.6 mg ml-1. Solubilities Ce at high pressures were also measured by in situ observation of the moving steps around equilibrium temperatures. The solubility decreased with increasing pressure.
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解説
  • 田村 勝弘
    17 巻 (2007) 1 号 p. 57-63
    公開日: 2007/04/12
    ジャーナル フリー
    We studied the lethal action of compressed oxygen gas on yeast cells and discussed its application to the sterilization processing of sudachi juice. The yeast cells (Candida boidinii SYM-1) suspended in sudachi juice could be sterilized completely when treated under the following conditions: 5.0 MPa for 15 min at 30°C, 10.0 MPa for 5 min at 40°C, and 5.0 MPa for less than 1 min at 50°C. Sudachi juice was sterilized by the treatment at 50°C without loss of vitamin C content. The removal of dissolved oxygen in sudachi juice by nitrogen gas pressurization was examined. The direct pressurization of sudachi juice with nitrogen gas decreased the amount of dissolved oxygen in it. When sudachi juice was compressed directly with nitrogen gas, more oxygen could be eliminated by applying higher nitrogen gas pressure and by taking longer time. Repetition of pressurization and depressurization with nitrogen gas could shorten the time to remove oxygen.
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連載解説「水素の話」(1)
  • 奥地 拓生, 鍵 裕之
    17 巻 (2007) 1 号 p. 65-72
    公開日: 2007/04/12
    ジャーナル フリー
    Neutron is a complementary probe to X-ray for material sciences at high pressure, especially for hydrogen compounds for which X-ray is less powerful than for the heavier elements. In addition, using the neutron probe it is easy to distinguish neighboring elements in the periodic table which is also difficult with X-ray. A spallation neutron source of new generation is now being constructed in Tokai, Ibaraki Pref. as a part of the J-PARC project. A proposal to build a dedicated high-pressure beamline at J-PARC was submitted, which has been successfully accepted in 2005 after the peer-review. In this article, we review some examples of scientific targets on material sciences of hydrogen compounds at high pressure, which will be newly revealed with this powerful neutron source and beamline.
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