Scientists get first look at how water 'lubricates' proteins

Nov 14, 2007

Scientists are one step closer to understanding how proteins move when they perform functions essential for supporting life. For the first time, scientists have directly observed how water lubricates the movements of protein molecules to enable different functions to happen.

In a paper published in the online early edition of the Proceedings of the National Academy of Sciences, Ohio State University researchers report using ultra-fast light pulses to reveal how water molecules link up with proteins and enable them to move and function.

The finding could one day help researchers find new treatments for diseases such as Alzheimer's, Parkinson's, cataracts, cystic fibrosis, and diabetes.

Proteins are complex molecules that form the main support structure for plant and animal cells, and they also regulate biochemical reactions. The shape and movements of a protein molecule determine its function, and scientists have long known that proteins can't function unless they are immersed in water.

“Protein-water interactions are a central, long-standing, unsolved problem in protein science,” said Dongping Zhong, associate professor of physics at Ohio State and leader of the study. “We believe that we are making a major step to answer these fundamental questions, and the final results will be very important for many biological applications.”

For instance, scientists could better understand how proteins fold and mis-fold -- a key to understanding certain diseases. They could also design more effective drug molecules that link up with proteins in just the right way.

Molecules move fast, shape-shifting in mere fractions of a second, so the movements are hard to see.

This study marks the first time scientists have been able to map the movements of water molecules at different sites on a much larger protein molecule, and see how those movements influence the form and function of the protein.

Zhong and his team took laser “snapshots” of a single myoglobin protein -- the protein that carries oxygen inside muscle tissue -- immersed in water in the laboratory. They were able to measure how fast the water molecules were moving around the protein, and see how those movements related to characteristics of the protein at that moment -- the electrical charge at a particular site, for instance, or changes in the protein's shape.

Proteins can execute a movement in a few billionths of a second. Water normally moves a thousand times faster -- on the scale of a trillionth of a second. In previous work, the Ohio State researchers showed that water molecules slow down substantially as they gets close to a protein.

This new study shows that the water molecules slow even more once they reach the protein. The water forms a very thin layer -- only three molecules thick -- around the protein, and this layer is key to maintaining the protein's structure and flexibility, lubricating its movements.

Their findings challenge the conventional wisdom of theorists who try to envision what is happening on these tiny scales. Because they can't directly see what's happening, scientists use simulations to fill the gap.

The simulation software has improved in recent years, Zhong said. But for two years his team has compared simulations to actual experiments, and found that the two don't match up.

“We are pretty confident at this point that the simulations need to change,” Zhong said. “Our experimental data provide a benchmark for testing and improving them.”

In the future, Zhong's team will study how water affects proteins interacting with each other, and with DNA.

“Our ultimate goal is to understand why water is so unique and important to life,” he said.

Source: Ohio State University

Explore further: Team invents microscopic sonic screwdriver

Related Stories

Waking proteins up from deep sleep to study their motions

Apr 30, 2015

In order to carry out their functions, proteins need to move. Scientists at EPFL have developed a new technique to study motions in proteins with unprecedented accuracy. The method, which is based on NMR, freezes proteins ...

Nature inspires first artificial molecular pump

May 19, 2015

Using nature for inspiration, a team of Northwestern University scientists is the first to develop an entirely artificial molecular pump, in which molecules pump other molecules. This tiny machine is no small ...

New link between ocean microbes and atmosphere uncovered

May 18, 2015

Few things are more refreshing than the kiss of sea spray on your face. You may not realize it, but that cool, moist air influences our climate by affecting how clouds are formed and how sunlight is scattered ...

Exposing breast cancer using nanoscale polymers

May 13, 2015

Photoacoustic imaging is a ground-breaking technique for spotting tumors inside living cells with the help of light-absorbing compounds known as contrast agents. A*STAR researchers have now discovered a way ...

Recommended for you

Researchers prove magnetism can control heat, sound

May 28, 2015

Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by ...

How researchers listen for gravitational waves

May 28, 2015

A century ago, Albert Einstein postulated the existence of gravitational waves in his General Theory of Relativity. But until now, these distortions of space-time have remained stubbornly hidden from direct ...

What's fair?: New theory on income inequality

May 27, 2015

The increasing inequality in income and wealth in recent years, together with excessive pay packages of CEOs in the U.S. and abroad, is of growing concern, especially to policy makers. Income inequality was ...

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such ...

User comments : 0

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.