Featured Research

from universities, journals, and other organizations

New method for watching proteins fold

Date:
December 23, 2011
Source:
University of Pennsylvania
Summary:
A protein's function depends on both the chains of molecules it is made of and the way those chains are folded. And while figuring out the former is relatively easy, the latter represents a huge challenge with serious implications because many diseases are the result of misfolded proteins. Now, a team of chemists has devised a way to watch proteins fold in "real-time," which could lead to a better understanding of protein folding and misfolding in general.

A protein's function depends on both the chains of molecules it is made of and the way those chains are folded. And while figuring out the former is relatively easy, the latter represents a huge challenge with serious implications because many diseases are the result of misfolded proteins. Now, a team of chemists at the University of Pennsylvania has devised a way to watch proteins fold in "real-time," which could lead to a better understanding of protein folding and misfolding in general.

Related Articles


The research was conducted by Feng Gai, professor in the Department of Chemistry in the School of Arts and Sciences, along with graduate students Arnaldo Serrano, also of Chemistry, and Robert Culik of the Department of Biochemistry and Molecular Biophysics at Penn's Perelman School of Medicine. They collaborated with Michelle R. Bunagan of the College of New Jersey's Department of Chemistry.

Their research was published in the international edition of the journal Angewandte Chemie, where it was featured on the cover and bestowed VIP (very important paper) status.

"One of the reasons that figuring out what happens when proteins fold is difficult is that we don't have the equivalent of a high-speed camera that can capture the process, " Gai said. "If the process were slow, we could take multiple 'pictures' over time and see the mechanism at work. Unfortunately, no one has this capability; the folding occurs faster than the blink of an eye."

Gai's team uses infrared spectroscopy -- a technique that measures how much light different parts of a molecule absorbs -- to analyze proteins' structure and how this changes. In this case, the researchers looked at a model protein known as Trp-cage with an infrared laser setup.

In this experiment, Gai's team used two lasers to study structural changes as a function of time. The first laser acts as the starting gun; by heating the molecule, it causes its structure to change. The second laser acts as the camera, following the motions of the protein's constituent amino acids.

"The protein is made of different groups of atoms, and the different groups can be thought of as springs," Gai said. "Each spring has a different frequency with which it moves back and forth, which is based on the mass of the atom on either end. If the mass is bigger, the spring oscillates slower. Our 'camera' can detect the speed of that motion and we can relate it to the atoms it is made of and how that segment of the protein chain moves."

Even in a simple protein like Trp-cage, however, there are many identical bonds, and the researchers need to be able to distinguish one from another in order to see which of them are moving while the protein folds. One strategy they used to get around this problem was to employ the molecular equivalent of a tracking device.

"We use an amino acid with a carbon isotope marker," Culik said. "If it's incorporated into the protein correctly, we'll know where it is."

With a single carbon atom of the Trp-cage slightly heavier than the others, the research team can use its signature to infer the position of the other atoms as they fold. The researchers could then "tune" the frequency of their laser to match different parts of the protein, allowing them to isolate them in their analyses.

Similar isotopes could be inserted in more complicated molecules, allowing their folds to also be viewed with infrared spectroscopy.

"This technique enhances our structural resolution. It allows us to see which part is moving," Gai said. "That would allow us to see exactly how a protein is misfolding in a disease, for example."

The research was supported by the National Institutes of Health.


Story Source:

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


Journal Reference:

  1. Robert M. Culik, Arnaldo L. Serrano, Michelle R. Bunagan, Feng Gai. Achieving Secondary Structural Resolution in Kinetic Measurements of Protein Folding: A Case Study of the Folding Mechanism of Trp-cage. Angewandte Chemie, 2011; 123 (46): 11076 DOI: 10.1002/ange.201104085

Cite This Page:

University of Pennsylvania. "New method for watching proteins fold." ScienceDaily. ScienceDaily, 23 December 2011. <www.sciencedaily.com/releases/2011/12/111223091457.htm>.
University of Pennsylvania. (2011, December 23). New method for watching proteins fold. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2011/12/111223091457.htm
University of Pennsylvania. "New method for watching proteins fold." ScienceDaily. www.sciencedaily.com/releases/2011/12/111223091457.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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