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 application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

White graphene makes ceramics multifunctional

16.01.2018 | Materials Sciences

Breaking bad metals with neutrons

16.01.2018 | Materials Sciences

ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records

16.01.2018 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>