Heat Resistant Enzymes
Posted August 1, 1998
Most proteins in living organisms begin to come apart when they are exposed to heat above 60°C. Yet, some organisms, including bacteria and worms live and flourish
on the edge of boiling hot springs or ocean floor steam vents at temperatures well above 60°C. What is different about the proteins, including the enzymes, in these organisms, that
allow them to exist and function at such high temperatures?
Studies published in March, 1998 have looked at an enzyme from a normal soil bacteria. By changing only eight out of hundreds of amino acids in the enzyme structure,
the scientists were able to change this enzyme from being unstable at temperatures above 80°C to being very stable at these same temperatures. These eight amino acids were in a region
of the enzyme structure that is thought to be the first to unfold when the enzyme is heated. By increasing the strength of the bonds that held the enzyme together (by changing the eight
amino acids), they were able to give the enzyme more heat resistance without changing its activity.
Since heat is used to increase the rate of many industrial reactions, the changing of enzymes to make them more heat tolerant has many possible applications. Heat
resistant enzymes can work in purifying wastewater, help laundry detergents work better, and aid in synthesizing new drugs. Heat stable enzymes tend to have a long shelf life, reducing
industrial costs. For these possible uses and others, biotechnology companies have been interested in studying the enzymes in microorganisms of Yellowstone National Park geysers.
Activity
An enzyme from the thermophilic bacteria Thermus aquaticus is used in the polymerase chain reaction to copy DNA. Find out why this heat-stable enzyme is
used and where these bacteria are normally found.
References
Wu, Corinna. "Hot-Blooded Proteins." Science News, Vol. 153, May 9, 1998, pp. 296-297
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