Weinger Joshua S, Parnell K Mark, Dorner Silke, Green Rachel, Strobel Scott A
Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, USA.
Nat Struct Mol Biol. 2004 Nov;11(11):1101-6. doi: 10.1038/nsmb841. Epub 2004 Oct 10.
The ribosome accelerates the rate of peptide bond formation by at least 10(7)-fold, but the catalytic mechanism remains controversial. Here we report evidence that a functional group on one of the tRNA substrates plays an essential catalytic role in the reaction. Substitution of the P-site tRNA A76 2' OH with 2' H or 2' F results in at least a 10(6)-fold reduction in the rate of peptide bond formation, but does not affect binding of the modified substrates. Such substrate-assisted catalysis is relatively uncommon among modern protein enzymes, but it is a property predicted to be essential for the evolution of enzymatic function. These results suggest that substrate assistance has been retained as a catalytic strategy during the evolution of the prebiotic peptidyl transferase center into the modern ribosome.
核糖体将肽键形成的速率提高了至少10^7倍，但其催化机制仍存在争议。在此，我们报告证据表明，一种tRNA底物上的一个官能团在该反应中发挥着至关重要的催化作用。将P位点tRNA的A76 2'-OH替换为2'-H或2'-F会导致肽键形成速率至少降低10^6倍，但不影响修饰后底物的结合。这种底物辅助催化在现代蛋白质酶中相对不常见，但它是一种据预测对酶功能进化至关重要的特性。这些结果表明，在从益生元肽基转移酶中心进化到现代核糖体的过程中，底物辅助作为一种催化策略被保留了下来。
