Washington: Scientists at the University of North Carolina at Chapel Hill have found that the time required for evolution on a warm Earth is shorter than critics might expect.
Enzymes, proteins that jump-start chemical reactions, are essential to life within cells of the human body and throughout nature.
Richard Wolfenden and his 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.
"That is a shocker. That``s what``s going to surprise people most, as it did me," Wolfenden said.
High temperatures were probably a crucial influence on reaction rates when life began forming in hot springs and submarine vents, Wolfenden said.
Later, the cooling of the earth provided selective pressure for primitive enzymes to evolve and become more sophisticated, the Wolfenden’s group hypothesizes.
Using two different reaction catalysts — which are not protein enzymes but that may have resembled early precursors to enzymes — the group put the hypothesis to the test. The catalyzed reactions are indeed far less sensitive to temperature, compared with reactions that are accelerated by catalysts. The results are consistent with our hypothesis, Wolfenden said.
These findings are likely to influence how scientists think of the first primitive forms of life on earth, and may affect how researchers design and enhance the power of artificial catalysts, he added.
The findings are published in the Dec. 1, 2010, online early edition of the Proceedings of the National Academy of Sciences.