9 September 1999

Amazing Molecular Mini Motors!

by Kate Melville

No it's not a solar powered Harley, it's a working, chemically powered molecular motor! Molecular motors enable bacteria and protozoa to speed through their environments and, in people are a key function for processes that range from muscle contraction to sperm swimming. This new molecular motor was designed and built by a team of researchers from Boston College, led by Dr. Ross Kelly and has been written up in the September 9 issue of Nature. The work was supported by the National Institute of General Medical Sciences (NIGMS and according to Dr. John Schwab, its program director, "This is significant from two points of view. One is that it proves we understand, at least in some sense, how nature might convert chemical energy into controlled motion." Secondly, "This is going orders of magnitude beyond nanotechnology, which we can visualize using optical microscopy or electron microscopy. We're taking it all the way to the single molecule level, which is quite exciting."

This advance should help researchers to better understand the molecular motors in muscles and the thread-like hairs called cilia inside lungs and other organs. It may also have applications in understanding diseases in which molecular motors are faulty, such as infertility, some respiratory and digestive disorders. The new mini motor is a small organic molecule containing less than 50 carbon atoms.

It operates as a unidirectional ratchet and is powered by a chemical called carbonyl dichloride. In contrast, nature's molecular motors are larger protein molecules fueled by the universal unit of cellular energy called adenosine triphosphate (ATP). It mimics the ability of molecular motors to convert chemical energy into ATP and therefore may help researchers understand the natural process at an atomic-level.

Dr. Kelly and his group are now modifying their motor to operate faster and to run continuously. In an interesting twist Dr Kelly sees that in addition to advancing the scientific understanding of molecular motors, the research is also part of a continuation of the historical efforts at miniaturisation. "The development of motors of ever diminishing size has riveted the attention of inventors since the achievement of steam engines Watt upwards of two centuries ago. Nobel laureate physicist Richard Feynman once posted a $1,000 prize for constructing an operating electric motor only 1/64 inch cube. The award was collected within the year!"