Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Ibaraki, Japan.
Frontier Research Center of Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai 319-1106, Ibaraki, Japan.
Biomolecules. 2022 Jan 7;12(1):95. doi: 10.3390/biom12010095.
The dynamic structure changes, including the unfolding, dimerization, and transition from the compact to the open-bundle unfolding intermediate structure of Cyt ', were detected by a small-angle neutron scattering experiment (SANS). The structure of Cyt ' was changed into an unstructured random coil at pD = 1.7 (R = 25 Å for the Cyt ' monomer). The four-α-helix bundle structure of Cyt ' at neutral pH was transitioned to an open-bundle structure (at pD ~13), which is given by a numerical partial scattering function analysis as a joint-clubs model consisting of four clubs (α-helices) connected by short loops. The compactly folded structure of Cyt ' (radius of gyration, R = 18 Å for the Cyt ' dimer) at neutral or mildly alkaline pD transited to a remarkably larger open-bundle structure at pD ~13 (R = 25 Å for the Cyt ' monomer). The open-bundle structure was also supported by ab initio modeling.
通过小角中子散射实验（SANS）检测到 Cyt' 的动态结构变化，包括展开、二聚化以及从紧密的束状展开中间结构向开放束状结构的转变。在 pH=1.7 时（Cyt' 单体的 R=25Å），Cyt' 的结构转变为无规卷曲。在中性 pH 下，Cyt' 的四-α-螺旋束结构转变为开放束结构（pD13），通过数值部分散射函数分析给出了一个联合球棒模型，由四个通过短环连接的球棒（α-螺旋）组成。在中性或弱碱性 pH 时，Cyt' 的紧密折叠结构（Cyt' 二聚体的回转半径，R=18Å）在 pD13 时转变为显著更大的开放束结构（Cyt' 单体的 R=25Å）。开放束结构也得到了从头计算建模的支持。
