TY - JOUR
T1 - Tryptophan 334 oxidation in bovine cytochrome c oxidase subunit I involves free radical migration
AU - Lemma-Gray, Patrizia
AU - Weintraub, Susan T.
AU - Carroll, Christopher A.
AU - Musatov, Andrej
AU - Robinson, Neal C.
N1 - Funding Information:
This work was supported by the National Institutes of Health (NIH GMS 24795), Robert A. Welch Foundation (AQ1481), American Heart Association – Texas Affiliate (0465099Y) and a Pilot Grant from Barshop Institute for Longevity and Aging Studies (AG013319-11). All mass spectra were acquired in the Institutional Mass Spectrometry Laboratory at The University of Texas Health Science Center in San Antonio. Some aspects of this work were presented in preliminary form at the 53rd ASMS Conference. The authors also thank Tiffany McDonald-Marsh for her technical assistance and Dr. LeAnn K. Robinson for editorial help in preparing the manuscript.
PY - 2007/2/6
Y1 - 2007/2/6
N2 - A single tryptophan (W334(I)) within the mitochondrial-encoded core subunits of cytochrome c oxidase (CcO) is selectively oxidized when hydrogen peroxide reacts with the binuclear center. W334(I) is converted to hydroxytryptophan as identified by reversed-phase HPLC-electrospray ionization tandem mass spectrometry analysis of peptides derived from the three SDS-PAGE purified subunits. Total sequence coverage of subunits I, II and III was limited to 84%, 66% and 54%, respectively. W334(I) is located on the surface of CcO at the membrane interface. Two other surface tryptophans within nuclear-encoded subunits, W48(IV) and W19(VIIc), are also oxidized when hydrogen peroxide reacts with the binuclear center (Musatov et al. (2004) Biochemistry 43, 1003-1009). Two aromatic-rich networks of amino acids were identified that link the binuclear center to the three oxidized tryptophans. We propose the following mechanism to explain these results. Electron transfer through the aromatic networks moves the free radicals generated at the binuclear center to the surface-exposed tryptophans, where they produce hydroxytryptophan.
AB - A single tryptophan (W334(I)) within the mitochondrial-encoded core subunits of cytochrome c oxidase (CcO) is selectively oxidized when hydrogen peroxide reacts with the binuclear center. W334(I) is converted to hydroxytryptophan as identified by reversed-phase HPLC-electrospray ionization tandem mass spectrometry analysis of peptides derived from the three SDS-PAGE purified subunits. Total sequence coverage of subunits I, II and III was limited to 84%, 66% and 54%, respectively. W334(I) is located on the surface of CcO at the membrane interface. Two other surface tryptophans within nuclear-encoded subunits, W48(IV) and W19(VIIc), are also oxidized when hydrogen peroxide reacts with the binuclear center (Musatov et al. (2004) Biochemistry 43, 1003-1009). Two aromatic-rich networks of amino acids were identified that link the binuclear center to the three oxidized tryptophans. We propose the following mechanism to explain these results. Electron transfer through the aromatic networks moves the free radicals generated at the binuclear center to the surface-exposed tryptophans, where they produce hydroxytryptophan.
KW - Aromatic pathway
KW - Cytochrome oxidase
KW - Hydrogen peroxide
KW - Mass spectrometry
KW - Proteolytic digestion
KW - Tryptophan oxidation
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U2 - 10.1016/j.febslet.2006.12.054
DO - 10.1016/j.febslet.2006.12.054
M3 - Article
C2 - 17239857
AN - SCOPUS:33846425366
VL - 581
SP - 437
EP - 442
JO - FEBS Letters
JF - FEBS Letters
SN - 0014-5793
IS - 3
ER -