CHAPEL HILL, N.C. -- There has been controversy about whether life originated in a hot or cold environment, and about whether enough time has elapsed for life to have evolved to its present complexity.
But new research at the University of North Carolina at Chapel Hill investigating the effect of temperature on extremely slow chemical reactions suggests that the time required for evolution on a warm earth is shorter than critics might expect.
The findings are published in the Dec. 1, 2010, online early edition of the Proceedings of the National Academy of Sciences.
Enzymes, proteins that jump-start chemical reactions, are essential to life within cells of the human body and throughout nature. These molecules have gradually evolved to become more sophisticated and specific, said lead investigator Richard Wolfenden, PhD, Alumni Distinguished Professor of biochemistry and biophysics at UNC School of Medicine.
To appreciate how powerful modern enzymes are, and the process of how they evolved, scientists need to know how quickly reactions occur in their absence.
Wolfenden's group measured the speed of chemical reactions, estimating that some of them take more than 2 billion years without an enzyme.
In the process of measuring slow reaction rates, "it gradually dawned on us that the slowest reactions are also the most temperature-dependent," Wolfenden said.
In general, the amount of influence temperature has on reaction speeds varies drastically, the group found. In one slow reaction, for instance, raising the temperature from 25 to 100 degrees Celsius increases the rate 10 million fold. "That is a shocker," Wolfenden said. "That's what's going to surprise people most, as it did me."
That is surprising, Wolfenden said, because a textbook rule in chemistry for more than a century has been that the influence of temperature is modest. In particular, a doubling in reaction rate occurs when
|Contact: Les Lang|
University of North Carolina School of Medicine