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 New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>