کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1392774 | 983770 | 2008 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: An Uncharged Amine in the Transition State of the Ribosomal Peptidyl Transfer Reaction An Uncharged Amine in the Transition State of the Ribosomal Peptidyl Transfer Reaction](/preview/png/1392774.png)
SummaryThe ribosome has an active site comprised of RNA that catalyzes peptide bond formation. To understand how RNA promotes this reaction requires a detailed understanding of the chemical transition state. Here, we report the Brønsted coefficient of the α-amino nucleophile with a series of puromycin derivatives. Both 50S subunit- and 70S ribosome-catalyzed reactions displayed linear free-energy relationships with slopes close to zero under conditions where chemistry is rate limiting. These results indicate that, at the transition state, the nucleophile is neutral in the ribosome-catalyzed reaction, in contrast to the substantial positive charge reported for typical uncatalyzed aminolysis reactions. This suggests that the ribosomal transition state involves deprotonation to a degree commensurate with nitrogen-carbon bond formation. Such a transition state is significantly different from that of uncatalyzed aminolysis reactions in solution.
Journal: - Volume 15, Issue 5, 19 May 2008, Pages 493–500