当前位置：
X-MOL 学术
›
J. Am. Chem. Soc.
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Theoretical Exploration of the Mechanism of Riboflavin Formation from 6,7-Dimethyl-8-ribityllumazine: Nucleophilic Catalysis, Hydride Transfer, Hydrogen Atom Transfer, or Nucleophilic Addition?
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2013-04-23 , DOI: 10.1021/ja402099f Martin Breugst 1 , Albert Eschenmoser 2 , K. N. Houk 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2013-04-23 , DOI: 10.1021/ja402099f Martin Breugst 1 , Albert Eschenmoser 2 , K. N. Houk 1
Affiliation
|
The cofactor riboflavin is biochemically synthesized by a constitutionally intricate process in which two molecules of 6,7-dimethyl-8-ribityllumazine react with each other to form one molecule of the cofactor and one molecule of 5-amino-6-(ribitylamino)uracil. Remarkably, this complex molecular transformation also proceeds non-enzymatically in boiling aqueous solution at pH 7.3. Four different mechanistic pathways for this transformation (nucleophilic catalysis, hydride transfer, hydrogen atom transfer, and a nucleophilic addition mechanism) have now been analyzed by density functional theory [M06-2X/def2-TZVPP/CPCM//M06-2X/6-31+G(d,p)/IEFPCM]. On the basis of these computational results, a so far unpublished nucleophilic addition mechanism is the lowest energy pathway yielding riboflavin. The previously proposed mechanism involving nucleophilic catalysis is higher in energy but is still a viable alternative for an enzyme-catalyzed process assisted by suitably positioned catalytic groups. Pathways involving the transfer of a hydride ion or of a hydrogen atom are predicted to proceed through higher energy transition states and intermediates.
中文翻译：
6,7-二甲基-8-核黄素形成机制的理论探索：亲核催化、氢化物转移、氢原子转移或亲核加成？
辅因子核黄素是通过结构复杂的过程进行生化合成的，其中两分子 6,7-二甲基-8-核黄素相互反应形成一分子辅因子和一分子 5-氨基-6-(ribitylamino)uracil . 值得注意的是，这种复杂的分子转化也在 pH 7.3 的沸腾水溶液中以非酶促方式进行。密度泛函理论[M06-2X/def2-TZVPP/CPCM//M06-2X/6-]分析了这种转化的四种不同机制途径（亲核催化、氢化物转移、氢原子转移和亲核加成机制） 31+G(d,p)/IEFPCM]。基于这些计算结果，迄今为止未发表的亲核加成机制是产生核黄素的最低能量途径。先前提出的涉及亲核催化的机制能量较高，但仍然是由适当定位的催化基团辅助的酶催化过程的可行替代方案。预计涉及氢阴离子或氢原子转移的途径将通过更高能量的过渡态和中间体进行。
更新日期：2013-04-23
中文翻译：
6,7-二甲基-8-核黄素形成机制的理论探索：亲核催化、氢化物转移、氢原子转移或亲核加成？
辅因子核黄素是通过结构复杂的过程进行生化合成的，其中两分子 6,7-二甲基-8-核黄素相互反应形成一分子辅因子和一分子 5-氨基-6-(ribitylamino)uracil . 值得注意的是，这种复杂的分子转化也在 pH 7.3 的沸腾水溶液中以非酶促方式进行。密度泛函理论[M06-2X/def2-TZVPP/CPCM//M06-2X/6-]分析了这种转化的四种不同机制途径（亲核催化、氢化物转移、氢原子转移和亲核加成机制） 31+G(d,p)/IEFPCM]。基于这些计算结果，迄今为止未发表的亲核加成机制是产生核黄素的最低能量途径。先前提出的涉及亲核催化的机制能量较高，但仍然是由适当定位的催化基团辅助的酶催化过程的可行替代方案。预计涉及氢阴离子或氢原子转移的途径将通过更高能量的过渡态和中间体进行。
京公网安备 11010802027423号