Oang Key Young, Kim Jong Goo, Yang Cheolhee, Kim Tae Wu, Kim Youngmin, Kim Kyung Hwan, Kim Jeongho, Ihee Hyotcherl
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon 305-701, Korea ; Department of Chemistry, Graduate School of Nanoscience & Technology (WCU), Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Korea.
Department of Chemistry, Inha University , Incheon 402-751, Korea.
J Phys Chem Lett. 2014 Mar 6;5(5):804-808. doi: 10.1021/jz4027425. Epub 2014 Feb 13.
Conformational substates of proteins are generally considered to play important roles in regulating protein functions, but an understanding of how they influence the structural dynamics and functions of the proteins has been elusive. Here, we investigate the structural dynamics of sperm whale myoglobin associated with the conformational substates using picosecond X-ray solution scattering. By applying kinetic analysis considering all of the plausible candidate models, we establish a kinetic model for the entire cycle of the protein transition in a wide time range from 100 ps to 10 ms. Four structurally distinct intermediates are formed during the cycle, and most importantly, the transition from the first intermediate to the second one ( → ) occurs biphasically. We attribute the biphasic kinetics to the involvement of two conformational substates of the first intermediate, which are generated by the interplay between the distal histidine and the photodissociated CO.
蛋白质的构象亚态通常被认为在调节蛋白质功能中起重要作用，但对于它们如何影响蛋白质的结构动力学和功能的理解一直难以捉摸。在这里，我们使用皮秒级X射线溶液散射研究了与构象亚态相关的抹香鲸肌红蛋白的结构动力学。通过应用考虑所有合理候选模型的动力学分析，我们建立了一个在从100皮秒到10毫秒的宽时间范围内蛋白质转变整个循环的动力学模型。在这个循环中形成了四种结构不同的中间体，最重要的是，从第一个中间体到第二个中间体的转变（→）是双相的。我们将双相动力学归因于第一个中间体的两种构象亚态的参与，它们是由远端组氨酸和光解离的一氧化碳之间的相互作用产生的。
