Structures and Formation Mechanisms of Folding Intermediates of Proteins

用溶液x射线散射法研究了不同蛋白质熔球（MG）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，另一类是由疏水核和扩尾组成的结构。一些MG主要通过疏水相互作用稳定，其他MG主要通过分子内SS键稳定。变性态不能用“随机线圈”一词来概括，因为变性态的结构多样性和多样性也被表明了。β -乳球蛋白折叠的动力学研究表明，具有非天然二级结构的中间体积累，这表明非分层模型对折叠的重要性。等温滴定量热法测定表明，MG中存在的疏水相互作用几乎是天然态的40%。结果表明，变性剂诱导的α -亚基变性为3态，而热变性为2态。对脯氨酸突变体的动力学研究表明，在色氨酸合酶α -亚基的折叠过程中存在两个连续的中间体。脯氨酸残基有助于后期中间体的稳定性。利用α -乳清蛋白的MG研究了伴侣氨酸识别靶标的机制，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。提出了不同蛋白质的MG模型，并将计算的散射曲线与观测的散射曲线进行了比较。因此，所提出的理论方法被证明是很有希望的折叠研究。研究了蛋白质溶液的高压核磁共振方法，并将其应用于RNase A的热变性。结果表明，RNase A在高压下也发生了两态转变。变性引起的体积变化为负，恒压下的热容也因压力的增加而显著降低。对变性后的绝热压缩率进行了精确测量。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