A Mass Spectrometric Approach for Probing the Stability of Bioorganic Radicals1. (20th January 2014)

• Record Type: Journal Article
• Authors: Tan, Lei; Hu, Hanfeng; Francisco, Joseph S.; Xia, Yu
• Is Part Of: Angewandte Chemie. Volume 126:Number 7(2014)
• Page Start: 1918
• Page End: 1921
• Publication Date: 2014-01-20
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201310480
• Languages: English
• ISSNs: 0044-8249

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl‐type radicals (X‐<sup>.</sup>CH‐Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas‐phase dissociation of cysteine sulfinyl radical (X‐Cys<alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sm9r5vk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:00448249:media:ANGE201310480:tex2gif-sup-2" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>SO</mml:mtext><mml:msup><mml:mtext> </mml:mtext><mml:mrow><mml:mtext>.</mml:mtext></mml:mrow></mml:msup></mml:mrow></mml:msup></mml:math></alternatives>‐Y) ions through homolysis of a C<sub>α</sub>C<sub>β</sub> bond. This fragmentation produces a glycyl‐type radical upon losing CH<sub>2</sub>SO, and the degree of this loss is closely tied to the stability of the as‐formed radical. Theoretical calculations indicate that the energy of the C<sub>α</sub>C<sub>β</sub> bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates.</p> </abstract>