Method determining single molecule chain charge state evolution in polyelectrolyte conformation conversion process

Abstract

The invention discloses a method determining single molecule chain charge state evolution in a polyelectrolyte conformation conversion process; the method imports a fluorescence fluctuation spectrum with the single molecule sensitivity to determine the charge state evolution on a single molecule level in a polyelectrolyte conformation conversion process. The method comprises the following steps: carrying out association analysis for fluorescence fluctuation signals so as to obtain molecule dimension information, thus expressing the molecule conformation conversion process; parsing the fluorescence fluctuation signal intensity distribution so as to obtain molecule brightness; comparing free fluorescence probe ions with probe ion brightness information, and combining with Boltzmann distribution treatment so as to obtain the polyelectrolyte molecule local electromotive force information, and thus obtaining the charge state evolution information in the whole molecule conformation conversion process. The method can be widely applied to charged characteristic researches on molecule comformational changes (like nucleic acid folding behaviors) in a multi-charge soft substance system and especially related to biology, and can provide guidance for designing intelligent nano-materials based on said characteristics.

Description

technical field [0001] The invention relates to a method for measuring the evolution of the charge state of a single molecular chain during the conformational transition of a polyelectrolyte, belonging to the fields of polymer physics and biophysics. Background technique [0002] The conformational transition of polyelectrolytes and the accompanying charge state evolution has been a fundamental hot topic in the fields of polymer physics and biophysics. The understanding of the conformational transition of polyelectrolytes, especially the folding / unfolding process of polyelectrolytes (such as DNA, protein) in living systems, not only plays an important role in the design and regulation of nano-smart materials, but will also contribute to the in-depth understanding of some basic life processes. However, the long-range electrostatic interaction brought about by the polyelectrolyte's own multi-charge characteristics and the large number of counter ions distributed around it bri...

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Problems solved by technology

[0003] The main methods used by the predecessors to explore the distribution of counter ions are: scattering methods, such as Lois Pollack of Cornell University in the United States, who used anomalous small-angle X-ray scattering (ASAXS) to obtain the counter ion in different conformational states. Ion spatial distribution information (Annual Review of Biophysics, 2011, 40, 225), Small Angle Scattering (SANS), DanielHerschlag et al. from Stanford University introduced buffer equilibrium-atomic emission spectroscopy (buffer equilibration-atomicemission spectroscopy; BE-AES) to obtain nucleic acid Quantitative information on the ion atmosphere of different conformational states such as B double-helix DNA (Methods in Enzymology, 2009, 469, 375.); Jean Duhamel et al. from the University of Waterloo, Canada developed the fluorescence blob model (FBM) to obtain the double-helix DNA Radial counter ion distribution (Journal of the American Chemical Society, 2012,134,16791); other methods such as NMR (such as 23 Na NMR), electron spin resonance spectroscopy, etc., but these methods are ensemble methods and cannot provide single-molecule information

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