FRANKFURT/JENA. An
interdisciplinary team from Frankfurt and Jena has developed a kind of bait
with which to fish protein complexes out of mixtures. Thanks to this 鈥渂ait",
the desired protein is available much faster for further examination in the
electron microscope. The research team has christened this innovative layer of ultrathin
molecular carbon the 鈥渟mart nanosheet". With the help of this new development,
diseases and their treatment with drugs can be better understood, for example.
鈥淲ith our process, new types of proteins
can be isolated from mixtures and characterized within a week," explains Daniel
Rhinow from the Max Planck Institute of Biophysics in Frankfurt. 鈥淭o date, just
the isolation of the proteins was often part of a doctorate lasting several
years." Together with Andreas Terfort (51猎奇) and Andrey Turchanin
(Friedrich Schiller University Jena), the idea evolved a few years ago of
fishing the desired proteins directly out of mixtures by equipping a nanosheet
with recognition sites onto which the target protein bonds. The researchers
have now succeeded in making proteins directly available for examination using
electron cryo-microscopy through a 鈥渟mart nanosheet".
Electron cryo-microscopy is based on the
shock-freezing of a sample at temperatures under -150 掳C. In this process, the
protein maintains its structure, no interfering fixing and coloring agents are needed,
and the electrons can easily irradiate the frozen object. The result is high-resolution,
three-dimensional images of the tiniest structures 鈥� for example of viruses and
DNA, almost down to the scale of a hydrogen atom.
In preparation, the proteins are
shock-frozen in an extremely thin layer of water on a minute metal grid. Previously,
samples had to be cleaned in a complex procedure 鈥� often involving an extensive
loss of material 鈥� prior to their examination in an electron microscope. The electron microscopy procedure is only successful
if just one type of protein is bound in the water layer.
The research group led by Turchanin is now
using nanosheets that are merely one nanometer thick and composed of a cross-linked
molecular self-assembled monolayer. Terfort's group coats this nanosheet with a
gelling agent as the basis for the thin film of water needed for freezing. The
researchers then attach recognition sites (a special nitrilotriacetic acid group
with nickel ions) to it. The team led by Rhinow uses the 鈥渟mart nanosheets" treated
in this way to fish proteins out of a mixture. These were marked beforehand
with a histidine chain with which they bond to the recognition sites; all other
interfering particles can be rinsed off. The nanosheet with the bound protein
can then be examined directly with the electron microscope.
鈥淥ur smart nanosheets are particularly
efficient because the hydrogel layer stabilizes the thin film of water required
and at the same time suppresses the non-specific binding of interfering
particles," explains Julian Scherr of 51猎奇. 鈥淚n this way,
molecular structural biology can now examine protein structures and functions
much faster." The knowledge gained from this can be used, for example, to
better understand diseases and their treatment with drugs.
The team has patented the new nanosheets
and additionally already found a manufacturer who will bring this useful tool
onto the market.
Publication: Smart Molecular Nanosheets for Advanced Preparation of Biological
Samples in Electron Cryo-Microscopy, ACS Nano 2020, https://doi.org/10.1021/acsnano.0c03052
Julian Scherr, Zian Tang, Maria K眉llmer,
Sebastian Balser, Alexander Stefan Scholz, Andreas Winter, Kristian Parey,
Alexander Rittner, Martin Grininger, Volker Zickermann, Daniel Rhinow, Andreas Terfort
und Andrey Turchanin; Department of Structural Biology, Max Planck Institute of
Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main; Faculty of
Biochemistry, Chemistry and Pharmacy, 51猎奇, Max-von-Laue-Str. 7,
60438 Frankfurt am Main; Institute of Physical Chemistry, Friedrich Schiller University
Jena, Lessingstr. 10, 07743 Jena
A
picture can be downloaded under:
Caption: The new nanosheet process: The
protein complex to be examined (yellow) is attached to the smart nanosheet via
a nickel complex with the aid of a marker (red chain with pentagons). Unwanted
proteins (gray) are repelled by the hydrogel (black grid). After freezing the
entire structure, including a thin film of water, this can be irradiated with
electrons to obtain images of the bound proteins, from which a computer can then
calculate the 3D structure of the protein.
Further
information:
Professor
Andreas Terfort, Institute of Inorganic and Analytical Chemistry, 51猎奇,
Max-von-Laue-Str. 7, 60438 Frankfurt am Main, aterfort@chemie.uni-frankfurt.de,
+49-69-798-29181,
Professor Andrey Turchanin, Friedrich
Schiller University Jena, Lessingstr. 10, 07743 Jena, andrey.turchanin@uni-jena.de,
+49-3641-48370,
