Based on single-molecule imaging: a new method of structural analysis.

The study of structure-to-function is of great significance to the field of biology.
since the three-dimensional structure of DNA was parsed, structural biology has helped scientists resolve the structure of more biological large molecules, solving many of the biological roots.
, the development of structural biology has been a major technical bottleneck.
the emergence of new technologies will bring leapfrog progress to the development of structural biology.
traditional structural analysis methods are X-ray diffraction and magnetic resonance imaging (NMR).
X-ray, through high-energy X-rays bombarding the crystals of biological large molecules, the signal of electron density can be obtained, thus creating three-dimensional coordinates of large molecules and analyzing relatively large molecular structures.
However, the method of X-ray imaging has some defects, first of all, X-ray diffraction needs to obtain large molecule crystals, which is quite difficult, and the crystal state of the large molecule composition may not be biologically active state, and the method can not solve the larger molecules.
NMR imaging uses the resonance of hydrogen nuclei in a strong magnetic field to obtain a signal that can resolve the three-dimensional structure of a molecule in a solution state.
but NMR is limited by the strength of a strong magnetic field and can only parse smaller biomass molecules, limiting the development of structural biology.
X-ray and NMR both have natural defects because structural biology wants to be able to obtain structures in the bioactive state of larger, polymers, and complexes.
, the long-established electron microscope (EM) has been widely used in structural biology in recent years, emerging ancient technologies.
more efficient and accurate computational refactoring methods with the emergence of more sensitive electronic detection probes, making the technology more promising.
this method does not require large molecules to form crystals, and combined with other sample preparation methods, frozen etched electron mirrors have become a hot topic in the field of single-molecule imaging and can be used to parse more than 50 thousand Daltons to thousands of Daltons of choice.
, however, there is also a problem with this method, which resolves the structure as the average composition of molecules, making the resulting mechanism more ambiguous.
the same problem exists for X-ray and NMR.
longchamp et al. have developed a new method of structural analysis, based on single-molecule imaging, which can parse the structural information of individual molecules, but not the average composition.
this method requires a special sample preparation method.
ion beams are required to softly land samples on ultra-clean graphene planes in ultra-vacuum environments.
because of the robust strength of graphene, the excellent transparency of the electron beam makes it a new darling in bioimaging and is also used for advanced cryographic etching electron imaging.
electroscopic imaging, the new method uses traditional, relatively weak electron beams to generate imaging signals and avoid damage to samples by high-intensity electron beams.
, CCD-based electronic detectors efficiently collect electronic scattering signals.
the ultra-clean graphene substation, as holographic imaging requires accurate subtracts of the electronic signal noise from the background.
the structure of a single molecule can be reconstructed mathematically after obtaining the electron signal by CCD.
Longchamp et al. invented a single-molecule holographic electron scattering imaging method has many benefits, first of all, the need for electron beam requirements are not high, so it will not be very expensive, and do not need to form crystals to image.
, low-energy electrons do not break the sample too much.
can reconstruct the three-dimensional structure of a single molecule, rather than the average structure, so that it can grasp the three-dimensional structure under the multiple forms of large molecules such as proteins, which is of great significance for structural biology and biophysics.
of course, the method can only obtain low-precision structure at present, more rigorous mathematical methods will help the method to obtain a better structure.
even though cryo-EM is now the same as mid-day, single-molecule holographic imaging technology is more representative of the future of structural biology.
may be the big development of structural biology in the near future.
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