March 23, 2009

Proteins may be used for drug delivery

U.S. scientists say they are studying motor proteins as possible nanoscale machines for drug delivery inside the body's cells.

Pennsylvania State University Associate Professor William Hancock said motor proteins, which transport chromosomes, mitochondria or bundles of proteins within cells, might be used to deliver drugs or even help inhibit tumor growth.

Hancock said most motor proteins contain two motor domains, or heads, attached to a shared cargo-binding domain, or tail.

Think of it as a freight train at the molecular level, he said, and it runs on cylindrical tracks -- or microtubules -- made of many protein subunits meshed together into a long polymer that is one ten-thousandth the diameter of hair.

Hancock and his colleagues are studying a particular motor protein known as kinesin-2, trying to understand the molecular mechanics of how the nanometer-scale proteins move.

The researchers believe the kinesin transport system might some day be engineered onto microchips.

Our idea is that you can hook up cargo -- drugs, antibodies, sequences of DNA or RNA -- and the motors would carry them through microchannels on a lab-on-a-chip type of device, said Hancock. We have already had success with incorporating these proteins into microengineered channels and achieving transport in these systems.

The research that included Gayatri Muthukrishnan, Yangrong Zhang and Shankar Shastry appeared in a recent issue of the journal Current Biology.