An Ionizable Active-Site Tryptophan Imparts Catalase Activity to a Peroxidase Core

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• 作者：Peter C. Loewen ; Xavi Carpena ; Pietro Vidossich ; Ignacio Fita ; Carme Rovira
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：May 21, 2014
• 年：2014
• 卷：136
• 期：20
• 页码：7249-7252
• 全文大小：311K
• 年卷期：v.136,no.20(May 21, 2014)
• ISSN：1520-5126

文摘

Catalase peroxidases (KatG鈥檚) are bifunctional heme proteins that can disproportionate hydrogen peroxide (catalatic reaction) despite their structural dissimilarity with monofunctional catalases. Using X-ray crystallography and QM/MM calculations, we demonstrate that the catalatic reaction of KatG鈥檚 involves deprotonation of the active-site Trp, which plays a role similar to that of the distal His in monofunctional catalases. The interaction of a nearby mobile arginine with the distal Met-Tyr-Trp essential adduct (in/out) acts as an electronic switch, triggering deprotonation of the adduct Trp.