Scientists seek enzymes
that don’t mind working
at high temperatures
By Rebecca Cheung
In the middle of a cattle ranch near Gerlach, Nev., enclosed by a corru- gated metal fence, are small pools of steaming water. Close to the surface
of these pools, water temperatures reach
about 90° Celsius; deeper down, it’s even
hotter. Landowners have sectioned off
the area around the pools and installed
an overflow pipe to keep the water from
seeping out and harming livestock
or people.
Despite the dangers involved, one September day Joel Graham leaned over the
barrier and plunged in his gloved hand to
scoop up sediment and water samples.
At this locale, the biologist from the
University of Maryland, Baltimore
was fishing for microorganisms that
can thrive at very high temperatures.
Such extremophiles contain reaction-driving proteins called enzymes unlike
any found in less harrowing environs.
Enzymes show up in all living
things— from the simplest microbes
to humans — and are essential for survival. They do jobs such as digesting
food and helping to make sure genetic
material gets properly copied. While a
lot of known enzymes live and work best
around the temperature of the human
body, Graham and colleagues are among
a cadre of scientists looking for new
enzymes that can function when conditions get superheated.
The collective hope? That such
enzymes could be co-opted to perform
industrial processes. In many of the
world’s factories, setting the thermostat on high keeps reactions moving
quickly and prevents bacteria and other
microbes from contaminating or eating up desired products. Papermaking,
textile manufacturing and some food
processing might all benefit from the
help of heat-loving enzymes.
Graham’s team is particularly interested in a class of enzymes that help
break down the grassy parts of plants,
an area where researchers have made
recent progress. Finding such enzymes,
and employing them in large quantities,
could lead to biofuel production on an
industrial scale, helping society reduce
its dependence on fossil fuels.
Some scientists are hoping a newly
discovered enzyme pulled from the field
may be an ideal high-temperature grass
muncher. Other researchers, instead of
getting their hands dirty in hot pools, are
designing never-before-seen heat-loving
Even when the heat is on, an enzyme
designed and created in the lab (ribbon
structure shown) can break down plant
material (sugar in orange).
enzymes in the lab. Many lab enzymes
are in some way inspired by versions
already found in nature.
“The environment contains a lot of
solutions to a lot of human problems,”
Graham says. “If you find a directed way
to go after what you’re looking for, it’s
actually not that hard to find something
new and useful.”
Enzyme-palooza
People have been using enzymes to perform chemical reactions outside the
body for millennia. Food processing with
enzymes, for example, dates back at least
4,000 years, when people stored milk in
the excised stomachs of animals. Digestive enzymes in an animal’s gut caused
milk to curdle, forming other dairy products like curds and whey.
Today, a cocktail of various proteins
help coagulate milk to make solid curds
for cheese. Other enzymes soften cotton
during textile manufacturing or treat
paper in the pulp industry. Enzymes
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