Inchworm movement of two rings switching onto a thread by biased Brownian diffusion represent a three-body problem
| Autor: | Amar H. Flood, Abhishek Singharoy, Elisabeth M. Fatila, Christopher Maffeo, Yun Liu, Edward G. Sheetz, Aleksei Aksimentiev, Christopher R. Benson |
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| Rok vydání: | 2018 |
| Předmět: |
Rotaxanes
Kinetics Catenanes Thread (computing) Molecular Dynamics Simulation 010402 general chemistry 01 natural sciences Biophysical Phenomena Artificial Molecular Machines Special Feature Diffusion Tetrazine chemistry.chemical_compound Motion Electrochemistry Brownian motion Physics Multidisciplinary 010405 organic chemistry Coupled motion Models Theoretical Three-body problem Molecular machine 0104 chemical sciences Classical mechanics chemistry Brownian dynamics Thermodynamics Algorithms |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America. 115(38) |
| ISSN: | 1091-6490 |
| Popis: | The coordinated motion of many individual components underpins the operation of all machines. However, despite generations of experience in engineering, understanding the motion of three or more coupled components remains a challenge, known since the time of Newton as the “three-body problem.” Here, we describe, quantify, and simulate a molecular three-body problem of threading two molecular rings onto a linear molecular thread. Specifically, we use voltage-triggered reduction of a tetrazine-based thread to capture two cyanostar macrocycles and form a [3]pseudorotaxane product. As a consequence of the noncovalent coupling between the cyanostar rings, we find the threading occurs by an unexpected and rare inchworm-like motion where one ring follows the other. The mechanism was derived from controls, analysis of cyclic voltammetry (CV) traces, and Brownian dynamics simulations. CVs from two noncovalently interacting rings match that of two covalently linked rings designed to thread via the inchworm pathway, and they deviate considerably from the CV of a macrocycle designed to thread via a stepwise pathway. Time-dependent electrochemistry provides estimates of rate constants for threading. Experimentally derived parameters (energy wells, barriers, diffusion coefficients) helped determine likely pathways of motion with rate-kinetics and Brownian dynamics simulations. Simulations verified intercomponent coupling could be separated into ring–thread interactions for kinetics, and ring–ring interactions for thermodynamics to reduce the three-body problem to a two-body one. Our findings provide a basis for high-throughput design of molecular machinery with multiple components undergoing coupled motion. |
| Databáze: | OpenAIRE |
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