Lasers prompt molecular metamorphosis

Chemists at Purdue University are using lasers to coax individual molecules to change their shape, a step that may someday enable scientists to direct molecules to perform specific functions.

A research team led by chemistry Professor Timothy Zwier has demonstrated how laser light can be used to prompt a large molecule to make alterations in its three-dimensional structure.

Large molecules, such as proteins, consist of polypeptide chains that twist and fold upon themselves to form a three-dimensional shape, or conformation. The molecules also can reconfigure into many different shapes. Such conformational changes can alter how a molecule reacts with other molecules.

Using laser light to excite a single chemical bond in a molecule that contained two peptide groups, Zwier’s team reportedly showed that they could change the preferred shape of the molecule simply by choice of laser wavelength.

The results suggest that scientists may someday be able to use laser light as a ‘switch’ to change a molecule’s structure, prompting it into action or altering its activity, Zwier says.

‘Clearly, we are still a long way from applying these methods directly to proteins or DNA or the like,’ he said. ‘Nevertheless, this approach may someday allow us to use a laser to directly manipulate the structure of molecules, and thereby turn on and off their functionality with light.’

The findings – currently on the Science Express Web site, http://www.scienceexpress.org – may provide fundamental information on the folding process used by proteins and other large molecules.

The study is also said to point to potential new avenues for developing applications for use in molecular electronic devices.

‘Scientifically, the study is interesting because not only is laser excitation efficient at driving conformational change, but it also achieves this change in a unique way,’ Zwier said.