The Mesomeric Effect of Thiazolium on non-Kekulé Diradicals in Pichia stipitis Transketolase

Ning Shian Hsu, Yung Lin Wang, Kuan Hung Lin, Chi Fon Chang, Syue Yi Lyu, Li Jen Hsu, Yu Chen Liu, Chin-Yuan Chang, Chang Jer Wu, Tsung Lin Li*

*此作品的通信作者

研究成果: Article同行評審

3 引文 斯高帕斯(Scopus)

摘要

It is theoretically plausible that thiazolium mesomerizes to congeners other than carbene in a low effective dielectric binding site; especially given the energetics and uneven electronegativity of carbene groups. However, such a phenomenon has never been reported. Nine crystal structures of transketolase obtained from Pichia stipitis (TKps) are reported with subatomic resolution, where thiazolium displays an extraordinary ring-bending effect. The bent thiazolium congeners correlate with non-Kekulé diradicals because there is no gain or loss of electrons. In conjunction with biophysical and biochemical analyses, it is concluded that ring bending is a result of tautomerization of thiazolium with its non- Kekulé diradicals, exclusively in the binding site of TKps. The chemophysical properties of these thiazolium mesomers may account for the great variety of reactivities carried out by thiamine–diphosphate-containing (ThDP) enzymes. The stability of ThDP in living systems can be regulated by the levels of substrates, and hydration and dehydration, as well as diradical-mediated oxidative degradation.

原文English
頁(從 - 到)1802-1807
頁數6
期刊Angewandte Chemie - International Edition
57
發行號7
DOIs
出版狀態Published - 12 2月 2018

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