Proteins are solids. When heated they do not melt; instead, they decompose or sublime directly to the gas phase at low pressures. They cannot be converted into a liquid form unless they are dissolved in a solvent.
A team at the University of Bristol (UK) and the Max Planck Institute of Colloids and Interfaces in Golm (Germany) has now successfully liquefied a protein without the assistance of a solvent. As the research team headed by Stephen Mann reports in the journal Angewandte Chemie, the trick is to modify the surface of the protein with a polymeric surfactant.
The researchers used ferritin for their experiments. This large protein serves animals and plants as a storage material for iron. Ferritin forms a hollow sphere that can hold thousands of iron ions. Adam Perriman, a researcher in the Mann lab, attached polymer chains consisting of a polyethylene oxide portion and a hydrocarbon portion to these iron-containing ferritin spheres. About 240 polymer chains were attached to every ferritin molecule. A solution of proteins modified in this way was freeze-dried.
The resulting dry powder could be melted to form a transparent, viscous red liquid that solidified only upon cooling to –50 °C. In the temperature range between 30 and 37 °C the modified protein is in a liquid-crystalline state, which means the molecules are oriented more or less uniformly but (at least partly) lack the three-dimensional lattice that is formed in the crystalline state. At higher temperatures, the modified protein acts like a normal liquid. It only decomposes at temperatures above 400 °C.
How does the liquefaction work? The surfactant chains on the ferritin surface keep the protein spheres apart and shield their surfaces. This prevents the electrostatic attractive forces between polar molecular groups of neighboring spheres from holding the proteins together in a solid. The spheres are instead held together by attractive forces between the hydrocarbon ends of the surfactant chains. These forces are only strong enough to hold the molecules together as a liquid. Between 30 and 37 °C the surfactant chains arrange themselves in an ordered pattern, giving the substance liquid-crystalline properties.
“This is a very exciting result with fundamental significance for understanding liquids comprising nanostructured components,” says Mann. “Also, it represents a possible way forward to a novel state of biomolecular matter, and could therefore have a number of important applications, for example in biomedical and sensor technology.”
Author: Stephen Mann, University of Bristol (UK), http://www.chm.bris.ac.uk/inorg/mann/webpage.htm
Title: Solvent-Free Protein Liquids and Liquid Crystals
Angewandte Chemie International Edition 2009, 48, No. 34, 6242–6246, doi: 10.1002/anie.200903100
Lipid nanodiscs stabilize misfolding protein intermediates red-handed
18.12.2017 | Technische Universität München
Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard
A study carried out by an international team of researchers and published in the journal Physical Review X shows that ion-trap technologies available today are suitable for building large-scale quantum computers. The scientists introduce trapped-ion quantum error correction protocols that detect and correct processing errors.
In order to reach their full potential, today’s quantum computer prototypes have to meet specific criteria: First, they have to be made bigger, which means...
Since 2016, German and Spanish researchers, among them scientists from the University of Göttingen, have been hunting for exoplanets with the “Carmenes”...
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
18.12.2017 | Information Technology
18.12.2017 | Physics and Astronomy
18.12.2017 | Agricultural and Forestry Science