A mass spectrometric approach for probing the stability of bioorganic radicals.
Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl-type radicals (X-(.) 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 SO .-Y) ions through homolysis of a Cα Cβ bond. This fragmentation produces a glycyl-type radical upon losing CH2 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 Cα Cβ 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.
Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA).
Lei
L
Tan
Hanfeng
H
Hu
Joseph S
JS
Francisco
Yu
Y
Xia
D005609:Free Radicals / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D005998:Glycine / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008958:Models, Molecular
D005609:Free Radicals; D005740:Gases; D005998:Glycine
captodative effect; mass spectrometry; radical ions; radicals