And third, the mechanism may include a substantial degree of both entropic and enthalpic contributions. In 1980, professor of molecular genetics Knud H. Nierhaus of the Max Planck Institute of Molecular Genetics, Berlin; chemistry professor Barry S. Cooperman of the University of Pennsylvania; and a coworker proposed that the ribosome's ability to properly orient two aminoacylated transfer RNA substrates in its peptidyl transferase center (active site) was sufficient to account for all of its catalytic power. This suggested a primarily entropic mechanism. The proposal received further support in 2000 and 2001, after atomic-level X-ray crystallographic structures of the ribosome were reported by three groups--a team led by professor of molecular biophysics and chemistry and Howard Hughes Medical Institute investigator Thomas A.
by STU BORMAN, C&EN WASHINGTON |
November 29, 2004