Keeping an eye on the surroundings

August 13, 2008
Kinetic terahertz absorption (KITA) uses a picosecond-duration terahertz pulse to monitor directly changes in solvent dynamics during molecular self-assembly on a reaction time scale of milliseconds to seconds. In their Communication, M. Gruebele and co-workers describe the application of this method to investigate the reorganization of solvent water during the folding of a protein (in this case ubiquitin). Credit: (C) Wiley-VCH 2008

Water is no passive spectator of biological processes; it is an active participant. Protein folding is thus a self-organized process in which the actions of the solvent play a key role. So far, the emphasis in studies of protein folding processes has been on observation of the protein backbone and its side chains. Researchers led by Martin Gruebele and Martina Havenith have now been able to detect changes in the protein–water network during protein folding in real time.

As they report in the journal Angewandte Chemie, this team of scientists at the University of Illinois (Urbana, USA) and the Ruhr University in Bochum (Germany) used a spectroscopic technique called KITA (kinetic terahertz absorption) to make their observations.

Terahertz (THz) radiation consists of electromagnetic waves in the submillimeter range, putting it between the infrared and microwave ranges. Efficient sources of THz radiation are now available, making it possible to directly measure the absorption of biomolecules in aqueous buffers on the picosecond time scale. Both the skeletal movements of proteins and the collective motions of water molecules surrounding proteins occur on this time scale.

The research team recently demonstrated that THz-range absorption spectroscopy is a sensitive method for the investigation of the water shell that surrounds proteins. In the layers immediately surrounding the protein, the water molecules are networked to each other differently than in pure water. Their absorption of THz radiation at certain frequencies is thus changed.

The way in which a protein folds to a very large extent determines its function. The folding process is very fast. The movements of the protein backbone influence the solvent, and the dynamics of the solvent can in turn influence the dynamics of the protein—thus playing an important role in the folding process. Kinetic THz absorption (KITA) registers the damping and phase-shifting of an electrical THz field caused by the folding of a protein. Comparison with results obtained by other methods confirms that KITA detects reorientations of the interactions between a protein and its water shell in an early phase of the folding process.

Source: Wiley

Explore further: A novel microscope for nanosystems

Related Stories

A novel microscope for nanosystems

June 24, 2015

Nanomaterials play an essential role in many areas of daily life. There is thus a large interest to gain detailed knowledge about their optical and electronic properties. Conventional microscopes get beyond their limits when ...

In water as in love, likes can attract

September 19, 2013

(Phys.org) —At some point in elementary school you were shown that opposite charges attract and like charges repel. This is a universal scientific truth – except when it isn't. A research team led by Berkeley Lab chemist ...

Tiny nanocubes help scientists tell left from right

June 27, 2013

(Phys.org) —In chemical reactions, left and right can make a big difference. A "left-handed" molecule of a particular chemical composition could be an effective drug, while its mirror-image "right-handed" counterpart could ...

Promoting poultry health through diet

February 25, 2013

Developing strategies to increase the amount of saleable product while reducing dietary inputs is a priority for animal scientists. University of Illinois researchers have been looking at how dietary components affect gut ...

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

A cataclysmic event of a certain age

July 27, 2015

At the end of the Pleistocene period, approximately 12,800 years ago—give or take a few centuries—a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

New blow for 'supersymmetry' physics theory

July 27, 2015

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

Dense star clusters shown to be binary black hole factories

July 29, 2015

The coalescence of two black holes—a very violent and exotic event—is one of the most sought-after observations of modern astronomy. But, as these mergers emit no light of any kind, finding such elusive events has been ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.