15N Solid-State NMR as a Probe of Flavin H-Bonding

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• 作者：Dongtao Cui ; Ronald L. Koder ; Jr. ; P. Leslie Dutton ; Anne-Frances Miller
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：June 23, 2011
• 年：2011
• 卷：115
• 期：24
• 页码：7788-7798
• 全文大小：975K
• 年卷期：v.115,no.24(June 23, 2011)
• ISSN：1520-5207

文摘

Flavins mediate a wide variety of chemical reactions in biology. To learn how one cofactor can be made to execute different reactions in different enzymes, we are developing solid-state NMR (SSNMR) to probe the flavin electronic structure, via the ¹⁵N chemical shift tensor principal values (未_ii). We find that SSNMR has superior responsiveness to H-bonds, compared to solution NMR. H-bonding to a model of the flavodoxin active site produced an increase of 10 ppm in the 未₁₁ of N5, although none of the H-bonds directly engage N5, and solution NMR detected only a 4 ppm increase in the isotropic chemical shift (未_iso). Moreover SSNMR responded differently to different H-bonding environments, as H-bonding with water caused 未₁₁ to decrease by 6 ppm, whereas 未_iso increased by less than 1 ppm. Our density functional theoretical (DFT) calculations reproduce the observations, validating the use of computed electronic structures to understand how H-bonds modulate the flavin鈥檚 reactivity.