Filming Chemical Reactions at the Single-molecule Level Using Electron Beam

Biological nanopores are a class of membrane proteins that open nanoscale water conduits in biological membranes. When they are reconstituted in artificial membranes and a bias voltage is applied across the membrane, the ionic current passing through individual nanopores can be used to monitor chemical reactions, to recognize individual molecules and, of most interest, to sequence DNA. In addition, a more recent nanopore application is the analysis of single proteins and enzymes. Monitoring enzymatic reactions with nanopores, i.e. nanopore enzymology, has the unique advantage that it allows long-timescale observations of native proteins at the single-molecule level. Here, we describe the approaches and challenges in nanopore enzymology. This article is part of the themed issue ‘Membrane pores: from structure and assembly, to medicine and technology’.

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Revealing the Thermodynamic Properties of Elementary Chemical Reactions at the Single-Molecule Level

The Journal of Physical Chemistry B ◽

10.1021/acs.jpcb.9b03474 ◽

2019 ◽

Vol 123 (29) ◽

pp. 6253-6259 ◽

Cited By ~ 1

Author(s):

Xiaodong Liu ◽

Tao Chen ◽

Prashant K. Jain ◽

Weilin Xu

Keyword(s):

Thermodynamic Properties ◽

Chemical Reactions ◽

Single Molecule ◽

Single Molecule Level ◽

Elementary Chemical

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Reaction of diphtheria toxin channels with sulfhydryl-specific reagents: observation of chemical reactions at the single molecule level.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.91.12.5272 ◽

1994 ◽

Vol 91 (12) ◽

pp. 5272-5276 ◽

Cited By ~ 31

Author(s):

J. A. Mindell ◽

H. Zhan ◽

P. D. Huynh ◽

R. J. Collier ◽

A. Finkelstein

Keyword(s):

Chemical Reactions ◽

Single Molecule ◽

Diphtheria Toxin ◽

Single Molecule Level

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The method of replication affects metal film granularity and resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155517 ◽

1989 ◽

Vol 47 ◽

pp. 708-709

Author(s):

George C. Ruben

Keyword(s):

Electron Beam ◽

High Resolution ◽

Film Thickness ◽

Single Molecule ◽

Metal Film ◽

Vertical Surface ◽

High Resolution Imaging ◽

Controllable Factors ◽

Resolution Imaging

Single molecule resolution in electron beam sensitive, uncoated, noncrystalline materials has been impossible except in thin Pt-C replicas ≤ 150Å) which are resistant to the electron beam destruction. Previously the granularity of metal film replicas limited their resolution to ≥ 20Å. This paper demonstrates that Pt-C film granularity and resolution are a function of the method of replication and other controllable factors. Low angle 20° rotary , 45° unidirectional and vertical 9.7±1 Å Pt-C films deposited on mica under the same conditions were compared in Fig. 1. Vertical replication had a 5A granularity (Fig. 1c), the highest resolution (table), and coated the whole surface. 45° replication had a 9Å granulartiy (Fig. 1b), a slightly poorer resolution (table) and did not coat the whole surface. 20° rotary replication was unsuitable for high resolution imaging with 20-25Å granularity (Fig. 1a) and resolution 2-3 times poorer (table). Resolution is defined here as the greatest distance for which the metal coat on two opposing faces just grow together, that is, two times the apparent film thickness on a single vertical surface.

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