Science unfolds shapes of life

The workings of life are bound up in the intricate folds of the long-chain polymers known as proteins. Yet science has been unable to predict how each one should shape up, writes Steve Farrar.

Now a team of physicists believe they have found an approach that could lead to an understanding of the ground rules of the origami of nature.

The human body has hundreds of thousands of different varieties of these remarkable molecules, which make up every living cell. Following a genetic recipe, each is built from a unique chain of tens of hundreds of amino acids.

The properties and functions of each protein are determined by its folded shape, and this is ultimately determined by the properties of the component amino acids.

But this formula has proved highly resistant to science.

Jayanth Banavar, professor of physics at Pennsylvania State University in the United States, and Amos Maritan, professor of physics at the International School for Advanced Studies, in Trieste, Italy, have led an effort to attack the problem.

They suggest that polymer chains - including proteins - should be thought of as tubes rather than as strings of beads as they have been previously.

This changes the basic mathematics of the model. Professor Banavar said that when the tube was tuned to be comparable to the scale at which component amino acids reacted with their surroundings, many well-known characteristics emerged.

The model molecules naturally fold themselves into a familiar repertoire of helices, hairpins and sheets - just as is observed.

They also possess the flexibility and versatility essential to their central role in life.

"It is an extremely simple idea that leads to a novel phase of matter that's tailor-made for nature to use for proteins," Professor Banavar said.

The results are published in the journal Proteins : Structure, Function and Genetics .

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Contact steve.farrar@thes.co.uk