Featured Research

from universities, journals, and other organizations

In protein folding, internal friction may play a more significant role than previously thought

Date:
April 24, 2012
Source:
University of California - Santa Barbara
Summary:
Researchers have reported a new understanding of a little-known process that happens in virtually every cell of our bodies.

An amino acid chain folding into a three-dimensional protein.
Credit: Benjamin Schuler

An international team of researchers has reported a new understanding of a little-known process that happens in virtually every cell of our bodies.

Protein folding is the process by which not-yet folded chains of amino acids assume their specific shapes, hence taking on their specific functions. These functions vary widely: In the human body, proteins fold to become muscles, hormones, enzymes, and various other components.

"This protein folding process is still a big mystery," said UC Santa Barbara physicist Everett Lipman, one of several authors of a paper, "Quantifying internal friction in unfolded and intrinsically disordered proteins with single-molecule spectroscopy." The paper was published in the Proceedings of the National Academy of Sciences.

A protein's final shape, said Lipman, is primarily determined by the sequence of amino acid components in the unfolded chain. In the process, the components bump up against each other, and when the right configuration is achieved, the chain passes through its "transition state" and snaps into place.

"What we would like to understand eventually is how the chemical sequence of a protein determines what it is going to become and how fast it is going to get there," Lipman said.

Using a microfluidic mixing technique pioneered in the UCSB physics department by former graduate student Shawn Pfeil, the research team, including collaborators from the University of Zurich and the University of Texas, was able to monitor extremely rapid reconfiguration of individual protein molecules as they folded.

In the microfluidic mixer, a "denaturant" chemical used to unravel the proteins was quickly diluted, enabling observation of folding under previously inaccessible natural conditions. The measurements demonstrated that internal friction plays a more significant role in the folding process than could be seen in prior experiments, especially when the protein starts in the more compact unfolded configuration it would have in a denaturant-free living cell.

"At those size scales, everything is dominated by friction," said Lipman, comparing the environment of a protein molecule in water to a human body in molasses. Friction between the molecule and its liquid environment is an issue, as well as the "dry" friction that is independent of the surrounding solvent.

Internal friction slows down the folding process by reducing the rate at which the amino acid chain explores different configurations that may lead to the transition state. The longer it takes to find its native state -- its final form -- the higher the likelihood it could get stuck in an unfolded state.

"When it is unfolded, it is more vulnerable to being trapped in a misfolded state, or to aggregation with other unfolded protein molecules," said Lipman. Aggregation of misfolded proteins is thought to be a contributor to many types of diseases, such as the amyloid plaques that are associated with Alzheimer's disease. Alternatively, the unfolded and not usable protein could be broken back up into its component amino acids by the cell.

While there is no confirmed link between internal friction and aggregation, or any pattern of friction for one protein that affects others in the same way, Lipman and his colleagues are getting closer to understanding the degree to which internal friction affects the protein folding process.

"These measurements show that under realistic conditions, internal friction plays a significant role in the dynamics of the unfolded state. If a model of the protein folding process doesn't account for this, it will need to be reconsidered," he said.


Story Source:

The above story is based on materials provided by University of California - Santa Barbara. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Soranno, B. Buchli, D. Nettels, R. R. Cheng, S. Muller-Spath, S. H. Pfeil, A. Hoffmann, E. A. Lipman, D. E. Makarov, B. Schuler. Quantifying internal friction in unfolded and intrinsically disordered proteins with single-molecule spectroscopy. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1117368109

Cite This Page:

University of California - Santa Barbara. "In protein folding, internal friction may play a more significant role than previously thought." ScienceDaily. ScienceDaily, 24 April 2012. <www.sciencedaily.com/releases/2012/04/120424142339.htm>.
University of California - Santa Barbara. (2012, April 24). In protein folding, internal friction may play a more significant role than previously thought. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2012/04/120424142339.htm
University of California - Santa Barbara. "In protein folding, internal friction may play a more significant role than previously thought." ScienceDaily. www.sciencedaily.com/releases/2012/04/120424142339.htm (accessed August 28, 2014).

Share This




More Plants & Animals News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Super Healthful Fruits and Vegetables: Which Are Best?

Super Healthful Fruits and Vegetables: Which Are Best?

Ivanhoe (Aug. 27, 2014) We all know that it is important to eat our fruits and vegetables but do you know which ones are the best for you? Video provided by Ivanhoe
Powered by NewsLook.com
Bad Memories Turn Good In Weird Mouse Brain Study

Bad Memories Turn Good In Weird Mouse Brain Study

Newsy (Aug. 27, 2014) MIT researchers were able to change whether bad memories in mice made them anxious by flicking an emotional switch in the brain. Video provided by Newsy
Powered by NewsLook.com
Do Couples Who Smoke Weed Together Stay Together?

Do Couples Who Smoke Weed Together Stay Together?

Newsy (Aug. 27, 2014) A study out of University at Buffalo claims couples who smoke marijuana are less likely to experience intimate partner violence. Video provided by Newsy
Powered by NewsLook.com
Panda Might Have Faked Pregnancy To Get Special Treatment

Panda Might Have Faked Pregnancy To Get Special Treatment

Newsy (Aug. 27, 2014) A panda in China showed pregnancy symptoms that disappeared after two months of observation. One theory: Her pseudopregnancy was a ploy for perks. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins