Nonlocal interactions stabilize compact folding intermediates in reduced unfolded bovine pancreatic trypsin inhibitor.
Nonlocal interactions stabilize compact folding intermediates in reduced unfolded bovine pancreatic trypsin inhibitor.
复制标题
非局部相互作用稳定了还原性未折叠牛胰腺胰蛋白酶抑制剂中的紧凑折叠中间体。
DOI：
10.1021/bi00164a009
复制
发表时间：
1992
期刊：
影响因子：
2.9
通讯作者：
Haas,E
中科院分区：
文献类型：
--
作者：
Gottfried,DS;Haas,E
1992年9月18日摘要：为了进一步理解蛋白质折叠过程，需要研究统计卷曲状态和折叠分子之间的结构中间体（平衡和动力学）。X射线晶体学和NMR结构研究无法确定蛋白质在变性溶液条件下的长程距离。然而，非辐射（福斯特）能量转移，已被证明是一个光谱标尺的距离分布和扩散之间的选择网站在蛋白质在一系列不同的solution条件下的测量。测量了N-末端残基处的供体探针与连接至还原和未折叠（在6 M盐酸胍和20 mM二硫苏糖醇中）牛胰蛋白酶抑制剂（BPTI）的四个赖氨酸残基（15、26、41、46）之一的受体之间的距离的分布作为温度的函数。即使在强变性剂和还原剂中，BPTI也不作为统计卷曲多肽存在。看来，非局部（长程）相互作用已经开始“折叠”的蛋白质向更紧凑，天然构象。随着温度的升高，疏水相互作用导致球状蛋白质的结构更加紧凑，这与相图的预测相一致。球状蛋白质的折叠途径是从未折叠状态通过折叠中间体转变为天然折叠状态。折叠途径的初始状态和中间状态都是蛋白质的非天然构象（Anfinsen，1961; Nemethy & Scheraga，1979; Kim & Baldwin，1982，1990; Ptitsyn，1987）。折叠转变是链段-链段和链-溶剂相互作用超过大量链熵的过程。在蛋白质折叠的最早的中间体自然是那些减少链熵显着超过那些中间体形成的折叠过渡的后期阶段。
Revised Manuscript Received September 18, 1992 abstract: To further our understanding of the protein folding process, it is desirable to examine the structural intermediates (equilibrium and kinetic) that are populated between the statistical coil state and the folded molecule. X-ray crystallography and NMR structural studies are unable to determine longrange distances in proteins under denaturing solution conditions. Nonradiative (Forster) energy transfer, however, has been shown to be a spectroscopic ruler for the measurement of distance distributions and diffusion between selected sites in proteins under a range of differentsolution conditions. The distributions of distances between a donor probe at the N-terminal residue and an acceptor attached to one of the four lysine residues (15, 26, 41, 46) of reduced and unfolded (in 6 M guanidine hydrochloride and 20 mM dithiothreitol) bovine pancreatic trypsin inhibitor (BPTI) were measured as a function of temperature. Even in strong denaturant and reducing agent, BPTI does not exist as a statistical coil polypeptide. It appears that nonlocal (long-range) interactions are already beginning to “fold" the protein toward a more compact, native conformation. As the temperature is increased under these conditions, hydrophobic interactions lead to an even more compact structure consistent with the predictions of phase diagrams for globular proteins.The folding pathway of a globular protein is a transition from an unfolded state, via folding intermediates, to the native folded state. Both the initial state and the intermediate states of the folding pathway are nonnative conformations of the protein (Anfinsen, 1961; Nemethy & Scheraga, 1979; Kim & Baldwin, 1982, 1990; Ptitsyn, 1987). The folding transition is a process in which chain segment-segment and chain-solvent interactions outweigh the large amount of chain entropy. The earliest intermediates in protein folding are naturally those which reduce the chain entropy significantly more than those intermediates formed in the later phases of the folding transition.