Structures and Formation Mechanisms of Folding Intermediates of Proteins

用溶液X射线散射法详细研究了不同蛋白质熔融小球的溶液结构。MG的结构可以分为两类：一类是接近天然结构的结构，另一类是由疏水的核心和张开的尾巴组成的(S)。一些MG主要通过疏水作用稳定，另一些MG主要通过分子内SS键稳定。变性状态不能用随机卷曲来概括，因为变性状态的结构多样性和多样性也被表明。动力学研究表明，具有非天然二级结构的中间体积累，这表明非层级模型对折叠的重要性。MG生成的等温滴定量热法测量表明，MG中存在的疏水相互作用几乎是天然状态下的40%。这表明变性剂诱导了Tryp…α亚基的变性更多的Tophane合成酶是3种状态，而它的热变性是2种状态。对脯氨酸突变体的动力学研究表明，色氨酸合成酶的α-亚基折叠过程中存在两个连续的中间体。利用α-乳清蛋白的MG研究了分子伴侣识别靶标的机理，揭示了静电相互作用的重要性，对MG的整体结构和决定因素进行了理论研究，特别是水对MG形成的贡献。建立了MG对不同蛋白质的散射模型，并将计算的散射分布与实际观测的散射分布进行了比较。建立了蛋白质溶液的高压核磁共振方法，并将其应用于核糖核酸酶A的热变性研究。结果表明，即使在高压下，核糖核酸酶A也会发生两态转变。随着压力的增加，变性的体积变化为负值，恒压热容也显著降低。精确测量了变性时的绝热压缩系数。较少

Solution structures of molten globules (MG) of various proteins were investigated in detail by solution X-ray scattering. The structure of MG can be classified into two categories : one is close to native structure and the other is composed of a hydrophobic core and flaring tail (s) . Some MG's are stabilized mainly by hydrophobic interaction, the other MG's are stabilized mainly by intramolecular SS bonds. The denatured states cannot be generalized by a term, random coil, because the structural diversity and variety in the denatured states were also indicated.Kinetic studies of beta-lactoglobulin folding demonstrated the accumulation of intermediate with non-native secondary structure, which suggests the importance of non-hierarchical model for folding. Isothermal titration calorimetric measurements on MG formation indicated that the hydrophobic interaction existed in MG is almost 40% of that in native state.It was revealed that denaturant-induced denaturation of alpha-subunit of tryp … More tophane synthase is 3 states, however its thermal denaturation is 2 states. Kinetic studies on proline mutants indicated the existence of two successive intermediates in the folding process of alpha-subunit of tryptophane synthase. Proline residues are contributed to the stability of the late intermediate.The mechanism of target recognition by chaperonine have been investigated using MG of alpha-lactalbumin to reveal the importance of electro-static interaction.Theoretical studies were performed on the global structures of MG and the determinant, especially the contribution of water to the MG formation. Models of MG were proposed to various proteins and the calculated scattering profiles were compared with the observed ones. Consequently the proposed theoretical method was turned out to be quite promising for the folding studies.High pressure NMR method for protein solution was developed and applied to thermal denaturation of RNase A.It was revealed that RNase A undergoes two-state transition even under high pressure. A volume change by denaturation was negative and also a heat capacity at constant pressure was decreased significantly by addition of pressure. Adiabatic compressibility upon denaturation was measured precisely. Less