Bedsprings aren't often found in biology. Now, chemists have succeeded in making a layer of tiny protein coils attached to a surface, much like miniature bedsprings in a frame. This thin film made of stable and very pure helices can help researchers develop molecular electronics or solar cells, or to divine the biology of proteins.
Physical chemists at the Department of Energy's Pacific Northwest National Laboratory pulled off this design trick using a "soft-landing" technique that disperses the tiny protein coils onto a waiting surface. The small proteins called peptides are of a variety that normally take the shape of a coiled spring or helix in gas phase. The method used by PNNL's Julia Laskin and Peng Wang delivered ultra-pure helical peptides to the surface and trapped them there, they report in July 29 and will appear in print in an upcoming issue of Angewandte Chemie.
"Controlling the conformation of peptides is not easy," said Laskin. "Our previous studies showed that soft-landing can be used to prepare ultrapure peptide layers on substrates. The question we faced was, in addition to controlling purity, can we also control the structure of the molecules? We showed we could."
To do so, Laskin and Wang began with peptides made almost entirely of the amino acid alanine. Due to alanine's chemical nature, long chains of it naturally form so-called á helices. The researchers ended the alanine chain with the amino acid lysine, which stabilizes the helix and allows the coiled chain to be chemically attached to the surface.
Working with a specially designed mass-selected ion deposition instrument at DOE's Environmental Molecular Sciences Laboratory on the PNNL campus, they deposited the peptides on the support layer in one of two ways, starting either from a liquid form for electrospray or from a gaseous mixture for soft-landing. In each case, the chemists began with the peptides (either in liquid or gas), zapped them to give them a slight electrical charge and blew them onto the surface.
When the chemists examined the peptide shapes in the solution and the resulting thin film, they found, unexpectedly, that most of the peptides failed to form helices. Instead, the majority of peptides took on a flat shape known as a â sheet. The dearth of helices in liquid form surprised the researchers.
When the researchers next used soft-landing to form thin layers, they didn't know if the peptides would form helices before landing on the surface. "Because we were starting from something that wasn't á-helical in solution, we were a little pessimistic whether it would work at all," Wang said.
But work it did. Depositing the peptides with soft-landing, the chemists found that nearly all of them alighted as helices. In addition, they could chemically connect the helices to the surface using a related technique called reactive-landing. When the chemists treated the thin layer with sound waves to test how easily the peptides fell off or changed shape, they found that some loosely bound peptides fell off, but those remaining maintained their helical forms.
"They formed a nicely organized, beautiful layer," says Wang.
Next, the team would like to create thin peptide layers using different support surfaces and a different mix of peptide shapes, to learn how to control the design of the thin films precisely.
"We found an interesting pathway to conduct different types of chemical reactions between complex molecules and substrates that will potentially enable us to prepare materials that cannot be made by standard methods," said Laskin.
"We hope to conduct lots of chemistry on the thin films," said Laskin -- chemistry that will let them spring forward into understanding biology and developing new materials.
Reference: P. Wang and J. Laskin, Helical Peptide Arrays on Self-Assembled Monolayer Surfaces through Soft and Reactive Landing of Mass-Selected Ions, Angewandte Chemie, online July 29, 2008, DOI 10.1002/anie.200801366 (http://dx.doi.org/10.1002/anie.200801366).
This work was supported by PNNL discretionary funding and DOE's Office of Basic Energy Sciences, part of the Office of Science.
The Environmental Molecular Sciences Laboratory is a national scientific user facility sponsored by the Department of Energy's Office of Science, Biological and Environmental Research program that is located at Pacific Northwest National Laboratory. EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. EMSL's technical experts and suite of custom and advanced instruments are unmatched. Its integrated computational and experimental capabilities enable researchers to realize fundamental scientific insights and create new technologies.
Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America's most intractable problems in energy, national security and the environment. PNNL employs 4,000 staff, has a $855 million annual budget, and has been managed by Ohio-based Battelle since the lab's inception in 1965.
Designer cells: artificial enzyme can activate a gene switch
22.05.2018 | Universität Basel
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
22.05.2018 | Life Sciences
22.05.2018 | Earth Sciences
22.05.2018 | Trade Fair News