Featured Research

from universities, journals, and other organizations

'Work environment' affects protein properties

Date:
July 3, 2014
Source:
Ruhr-Universitaet-Bochum
Summary:
The function of proteins, which fulfill various tasks inside the cells, is often analyzed in aqueous buffer solutions. However, it is not known, for example in case of pharmaceutical studies, if they work in the same way in those solutions as in their natural environment: the cytoplasm is highly crowded with biomolecules, organic and inorganic substances. Researchers have now demonstrated that the water surrounding the dissolved substances inside the cell plays a crucial role with regard to protein stability, which has frequently been neglected in the past.

The function of proteins, which fulfil various tasks inside the cells, is often analysed in aqueous buffer solutions. However, it is not known, for example in case of pharmaceutical studies, if they work in the same way in those solutions as in their natural environment: the cytoplasm is highly crowded with biomolecules, organic and inorganic substances. Under the tutelage of Junior Professor Dr Simon Ebbinghaus, researchers from Bochum have demonstrated that the water surrounding the dissolved substances inside the cell plays a crucial role with regard to protein stability, which has frequently been neglected in the past. The researchers have published the results of their study, gained by means of simple model systems and thermodynamic analyses, in the Journal of the American Chemical Society (JACS). The results have been obtained following a collaboration under the umbrella of the Excellence Cluster RESOLV.

Proteins' work environment more viscous than egg white

Proteins are among the most important and most-studied biomolecules in biochemical research. They fulfill structure-relevant tasks and are the cells' molecular machines: catalysing chemical reactions, transporting metabolic products and identifying metabolites. Consequently, deficiencies of protein function often result in severe disorders, e.g. Huntington's and Alzheimer's disease. The proteins' natural work environment inside the cell is a highly crowded solution (more viscous and more highly concentrated than egg white), consisting of various macromolecules as well as small organic and inorganic substances. In order to study protein function using modern analytical methods, researchers often purify proteins in vitro and study them in diluted aqueous solution. However, it often cannot be precisely ascertained to what extent the experimental results reflect the actual function within the cellular environment.

Theory: in narrow spaces, proteins "tuck in their elbows"

A method frequently used for predicting the effect a densely-packed cellular environment has on proteins is the so-called excluded volume theory. It can be best explained using the example of an everyday phenomenon. In a crowded lift or on a crowded train, everybody attempts to avoid direct contact with their neighbours and to assume as compact a posture as possible (e.g. by tucking in their arms). According to the excluded volume theory, the principle of mutual repulsion can be applied to proteins in a densely-packed cellular environment. They assume a compact structure. As a rule, their biologically active status is at the same time their most compact status, which is why the excluded volume theory predicts a stabilisation of the biologically active status.

The study demonstrates that there are more factors at work than just mutual repulsion

Deploying various solvent additives, such as biomacromolecules, sugars and salts, the RUB researchers have imitated various cellular conditions and analysed the way they affect the model protein ubiquitin. They demonstrated that the proteins' behaviour is affected by more than just mutual repulsion between protein and solvent additive. In thermodynamic studies, different stabilisation and destabilisation mechanisms were discovered. Contrary to the expected so-called entropic stabilisation -- based on the excluded volume effect -- the researchers observed a so-called enthalpic stabilisation of ubiquitin in the presence of macromolecules, sugars and salts. Enthalpic stabilisation is directly correlated to the strengthening of the chemical bonds in the biologically active status and cannot be explained away with the protein's more compact shape being purely volume-based.

Water as mediator between protein and dissolved substances

The researchers attribute the enthalpic stabilisation phenomenon to a water-mediated process: protein and solvent additive do not interact directly, but following a modification of the water properties of the solvent additives' hydration water, the hydrogen bridge bonds in the protein's biologically active status are optimised. The project was financed by the Returnee Programme of the Ministry for Innovation, Science and Research of North Rhine-Westphalia, the Excellence Cluster RESOLV and the Chemical Industry Association (Verband der Chemischen Industrie e.V., VCI).


Story Source:

The above story is based on materials provided by Ruhr-Universitaet-Bochum. Note: Materials may be edited for content and length.


Cite This Page:

Ruhr-Universitaet-Bochum. "'Work environment' affects protein properties." ScienceDaily. ScienceDaily, 3 July 2014. <www.sciencedaily.com/releases/2014/07/140703091649.htm>.
Ruhr-Universitaet-Bochum. (2014, July 3). 'Work environment' affects protein properties. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2014/07/140703091649.htm
Ruhr-Universitaet-Bochum. "'Work environment' affects protein properties." ScienceDaily. www.sciencedaily.com/releases/2014/07/140703091649.htm (accessed October 22, 2014).

Share This



More Plants & Animals News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Cadaver Dogs Aid Search for More Victims of Suspected Indiana Serial Killer

Cadaver Dogs Aid Search for More Victims of Suspected Indiana Serial Killer

Reuters - US Online Video (Oct. 21, 2014) Police in Gary, Indiana are using cadaver dogs to search for more victims after a suspected serial killer confessed to killing at least seven women. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
White Lion Cubs Unveiled to the Public

White Lion Cubs Unveiled to the Public

Reuters - Light News Video Online (Oct. 21, 2014) Visitors to Belgrade zoo meet a pair of three-week-old lion cubs for the first time. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
'Cadaver Dog' Sniffs out Human Remains

'Cadaver Dog' Sniffs out Human Remains

AP (Oct. 21, 2014) Where's a body buried? Buster's nose can often tell you. He's a cadaver dog, specially trained to find human remains and increasingly being used by law enforcement and accepted in courts. These dogs are helping solve even decades-old mysteries. (Oct. 21) Video provided by AP
Powered by NewsLook.com
White Lion Cubs Born in Belgrade Zoo

White Lion Cubs Born in Belgrade Zoo

AFP (Oct. 20, 2014) Two white lion cubs, an extremely rare subspecies of the African lion, were recently born at Belgrade Zoo. They are being bottle fed by zoo keepers after they were rejected by their mother after birth. Duration: 00:42 Video provided by AFP
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


Plants & Animals

Earth & Climate

Fossils & Ruins

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