Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Protein folding hits a speed limit

08.05.2003


To carry out their functions, proteins must first fold into particular structures. How rapidly this process can occur has been both a source of debate and a roadblock to comparing protein folding theory and experiment.



Now, researchers at the University of Illinois at Urbana-Champaign have observed a protein that hit a speed limit when folding into its native state.

"Some of our proteins were folding as fast as they possibly could -- in only one or two microseconds," said Martin Gruebele, an Illinois professor of chemistry, physics and biophysics. A paper describing the work is to appear in the May 8 issue of the journal Nature.


To study protein folding at the speed limit, Gruebele and graduate student Wei Yuan Yang took a small protein and, by replacing some of the amino acids with others that improved the molecular interactions, made it fold faster. By the time they finished souping up their protein, it was folding nearly 1,000 times faster than normal.

The researchers then used a fast temperature-jump procedure to measure folding times with nanosecond resolution. To initiate the folding sequence, a solution of unfolded proteins was heated rapidly by a single pulse from an infrared laser. As the proteins twisted into their characteristic shapes, pulses from an ultraviolet laser caused some of the amino acids to fluoresce, revealing a time-sequence of folding events.

"Because a protein can follow more than one pathway to its native state, a variety of folding times will result," Gruebele said. "Plotting these times usually yields an exponential decay rate, because we are averaging over lots of molecules at once."

But, in addition to the normal exponential decay rate -- which did not exceed 10 microseconds -- Gruebele and Yang detected a much faster behavior that occurred on shorter time scales below one or two microseconds.

"That’s the speed limit," Gruebele said. "That’s the speed at which segments of the protein can physically change their positions -- the speed at which the protein would fold if it took the shortest possible path and made the least possible mistakes."

Before the experiment, time estimates ranged from as little as 10 nanoseconds to as long as 100 microseconds, Gruebele said. The right answer lay in the middle of that range.

"Of course, different proteins will have different speed limits," Gruebele said. "Longer molecules have to move around more to fold, and therefore have slower speed limits."

By modifying their protein to fold extremely fast over a reduced energy barrier, the researchers moved from timing macroscopic kinetics of protein folding over an energy barrier to timing the movement of the protein’s polymer chain. This molecular time scale is also where transition state theory breaks down.

"Because we can measure both the molecular time scale and the activated kinetics normally associated with transition state theory in one experiment, we can determine the activation energy on an absolute scale," Gruebele said. "This allows us to directly compare experimental and computational folding rates, and therefore calibrate the theory."


The Camille and Henry Dreyfus Foundation funded the work.

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu/

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>