Reaction of AdoMet with ThiC Generates a Backbone Free Radical

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• 作者：N. Cecilia Martinez-Gomez ; Russell R. Poyner ; Steven O. Mansoorabadi ; George H. Reed ; Diana M. Downs
• 刊名：Biochemistry
• 出版年：2009
• 出版时间：January 20, 2009
• 年：2009
• 卷：48
• 期：2
• 页码：217-219
• 全文大小：201K
• 年卷期：v.48,no.2(January 20, 2009)
• ISSN：1520-4995

文摘

ThiC is an [4Fe-4S] cluster protein that catalyzes the formation of 4-amino-5-hydroxymethyl-2-methylpyrimidine. EPR spectroscopic studies demonstrate that, upon interaction with AdoMet, active ThiC from Salmonella enterica generates a persistent free radical on the α-carbon of an amino acid residue. The EPR properties of the radical are consistent with any residue other than a Gly or Ala. Exposure to oxygen was accompanied by a fission of the radical-carrying polypeptide chain between the Gly436 and His437 residues in ThiC. Regardless of whether the backbone radical is part of the catalytic machinery, its presence provides evidence that ThiC employs free radical chemistry as expected for radical SAM enzymes.