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

(Santa Barbara, Calif.) 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.

Contact: Sonia Fernandez
University of California - Santa Barbara

Related biology news :

1. Photonic crystal biosensors detect protein-DNA interactions
2. Penn biophysicists create new model for protein-cholesterol interactions in brain and muscle tissue
3. Dont forget the vitamin A when working with its carrier protein
4. Saliva proteins could help detection of oral cancer
5. The structure of the Mre11 protein bound to DNA
6. New lab manual focuses on essential methods for purifying and characterizing proteins
7. Proteins in sperm unlock understanding of male infertility says new study
8. Response to immune protein determines pathology of multiple sclerosis
9. Columbia to award 2008 Horwitz Prize to Arthur Horwich & Ulrich Hartl for cellular protein folding
10. Human protein atlas will help pinpoint disease
11. How neuronal activity leads to Alzheimers protein cleavage
Post Your Comments:
Related Image:
In protein folding, internal friction may play a more significant role than previously thought
(Date:11/12/2015)... Nov. 11, 2015   Growing need for ... tools has been paving the way for use ... of discrete analytes in clinical, agricultural, environmental, food ... predominantly used in medical applications, however, their adoption ... due to continuous emphasis on improving product quality ...
(Date:11/9/2015)... , Nov. 9, 2015  Synaptics Inc. (NASDAQ: ... today announced broader entry into the automotive market with ... match the pace of consumer electronics human interface innovation. ... are ideal for the automotive industry and will be ... Europe , Japan ...
(Date:10/29/2015)... , Oct. 29, 2015 Daon, a global ... it has released a new version of its ... North America have already installed ... also includes a FIDO UAF certified server component ... preparing to activate FIDO features. These customers include some ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... 24, 2015 SHPG ) announced today that ... Piper Jaffray 27 th Annual Healthcare Conference in ... at 8:30 a.m. EST (1:30 p.m. GMT). --> SHPG ... will participate in the Piper Jaffray 27 th Annual Healthcare ... Tuesday, December 1, 2015, at 8:30 a.m. EST (1:30 p.m. GMT). ...
(Date:11/24/2015)... 24, 2015  Tikcro Technologies Ltd. (OTCQB: TIKRF) today announced that its ... at 11:00 a.m. Israel time, at the law ... Allon Street, 36 th Floor, Tel Aviv, Israel ... and Izhak Tamir to the Board of Directors; ... directors; , approval of an amendment to certain terms of options ...
(Date:11/24/2015)... Nov. 24, 2015  Twist Bioscience, a company ... Leproust, Ph.D., Twist Bioscience chief executive officer, will ... on December 1, 2015 at 3:10 p.m. Eastern ... City. --> --> ... Twist Bioscience is on Twitter. Sign up to ...
(Date:11/24/2015)... ... ... InSphero AG, the leading supplier of easy-to-use solutions for production, culture, and assessment ... Chief Operating Officer. , Having joined InSphero in November 2013 as Business ... to Head of InSphero Diagnostics in 2014. There she has built up the ...
Breaking Biology Technology: