A use for buckyballs?
economist.com
"A similar technique may at last yield a use for
buckminsterfullerene, the soccer-ball-shaped molecule made of
60 carbon atoms that has been the focus of much hope and
hype from nanotechnologists ever since its discovery in 1985.
Stephen Wilson, a chemist at New York University, discovered
that the surface of the fullerene molecule could be used as a
scaffold to support other molecules. In collaboration with some
other chemists interested in nanotechnology, he founded
C-Sixty, a firm based in Toronto, that is now developing the
first fullerene-based drug candidates.
So far, C-Sixty's most promising bet is an anti-AIDS drug that
consists of a fullerene with dendrimers stuck on either side,
rather like antlers. Since the dendrimers are water-soluble, the
whole complex can dissolve in biological fluids, which fullerene
alone cannot.
Dr Wilson and his colleagues have discovered that the complex
finds its way to the active site of a viral enzyme known as
reverse transcriptase. This enzyme is critical to the life cycle of
HIV, the virus that causes AIDS, because it translates the
virus's genetic material into DNA, which the host cell then
unwittingly uses to make more viruses. C-Sixty's
fullerene-based drug scuppers this process by settling snugly
into the enzyme's active site, stopping it functioning.
That is not so different from the method of action of an
existing class of anti-AIDS drugs known as protease inhibitors.
These work by binding chemically to that enzyme's active site
to inhibit its action. (Protease cuts the raw chain of virus
protein produced by a subverted cell into functional molecules.)
However, the mechanism is not quite identical. Instead of
binding chemically, C-Sixty's fullerene drug forms a mechanical
plug for the active site. It is therefore less sensitive to the
precise chemical make-up of the site.
The reason this may be important is that strains of HIV which
are resistant to protease drugs are beginning to emerge. Uri
Sagman, C-Sixty's boss, says that it might be more difficult
for HIV to develop resistance to a fullerene-based drug than to
existing drugs, because an enzyme would have to undergo a
drastic change in shape to confound the fullerene, whereas a
few minor mutations are enough to render an existing
chemical-binding-based drug ineffective. Besides the
evolutionary odds against such a drastic change happening, a
big alteration in the shape of its active site might well render
an enzyme—and thus the virus—ineffective." |
