A report on the findings by Drs. Annette Sievers and Richard Wolfenden of the UNC School of Medicine appears in the new issue of the Proceedings of the National Academy of Sciences.
Besides Sievers and Wolfenden, report authors are doctoral student Malte Beringer and Dr. Marina V. Rodnina of the University of Witten/Herdecke in Witten, Germany.
"Enzymes, of which we have hundreds, participate chemically in the transformation of biological molecules by making and breaking bonds," said Wolfenden, Alumni Distinguished professor of biochemistry and biophysics. "A hallmark of that direct chemical involvement is that their catalytic effects are extremely temperature dependent. The question was whether the ribosome acts as an enzyme since there has been considerable interest in whether this particle does that."
Ribosomes are critical sites of protein synthesis, he said. Inside those particles, amino acids are laid down in proteins in the order specified by the genetic code.
In general, enzymes, which are biological catalysts, facilitate a chemical transformation by lowering the energy barrier, Sievers said.
"One can imagine this as two paths over a mountain," she said. "The path without the enzyme is much higher, and so it takes more energy to cross the mountain. The path on the enzyme is lower, and so it is easier to follow it."
Energy has two components, Sievers said. One is heat (enthalpy), the other one refers to the order of a system (entropy). It's possible for an enzyme to lower either of those energy components. Direct chemical involvement of an enzyme is characterized by lowering
'"/>
Contact: David Williamson
919-962-8596
University of North Carolina at Chapel Hill
10-May-2004