Manganese Superoxide Dismutase Gene (SOD2) Polymorphism and Exudative Age-related Macular Degeneration in the Japanese Population
- 作者：Norimoto Gotoh ; Ryo Yamada ; Fumihiko Matsuda ; Nagahisa Yoshimura ; Tomohiro Iida
- 关键词：CHEMBIO ; RNA
- 刊名：American Journal of Ophthalmology
- 出版年：2008
- 期刊代码：7_00029394
- 类别：med
- 出版时间：July 2008
- 卷：146
- 期：1
- 页码：146
- 文件大小：43 K
摘要
The 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 
-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.
-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.