TY - JOUR
T1 - Unexpected light emission from tyrosyl radicals as a probe for tyrosine oxidation
AU - Ignasiak, Marta
AU - Frackowiak, Kamil
AU - Pedzinski, Tomasz
AU - Davies, Michael J.
AU - Marciniak, Bronisław
PY - 2020
Y1 - 2020
N2 - Tyrosine residues (Tyr) on proteins are a favoured site of one-electron oxidation due to their low one-electron reduction potentials. In this work, light-induced oxidation of Tyr residues was investigated using direct ionisation (via 266 nm light excitation) and sensitized photo-oxidation (by 3-carboxybenzophenone as sensitizer and 355 nm). Light emission (fluorescence) was observed at 410–440 nm as a result of Tyr oxidation. This novel light emission process is shown to be dependent on the solvent and aromatic ring substituents, however it does not depend on pH. It is proposed, that after initial formation of tyrosine phenoxyl radicals (TyrO●) by one electron-oxidation, the TyrO● absorbs a second photon to give an excited state species that undergoes subsequent light emission. The intensity of this emission depends on the Tyr concentration, and the detection of this emission can be used to identify and quantify one-electron formation of oxidized Tyr residues on proteins.
AB - Tyrosine residues (Tyr) on proteins are a favoured site of one-electron oxidation due to their low one-electron reduction potentials. In this work, light-induced oxidation of Tyr residues was investigated using direct ionisation (via 266 nm light excitation) and sensitized photo-oxidation (by 3-carboxybenzophenone as sensitizer and 355 nm). Light emission (fluorescence) was observed at 410–440 nm as a result of Tyr oxidation. This novel light emission process is shown to be dependent on the solvent and aromatic ring substituents, however it does not depend on pH. It is proposed, that after initial formation of tyrosine phenoxyl radicals (TyrO●) by one electron-oxidation, the TyrO● absorbs a second photon to give an excited state species that undergoes subsequent light emission. The intensity of this emission depends on the Tyr concentration, and the detection of this emission can be used to identify and quantify one-electron formation of oxidized Tyr residues on proteins.
UR - http://www.scopus.com/inward/record.url?scp=85083383472&partnerID=8YFLogxK
U2 - 10.1016/j.freeradbiomed.2020.03.022
DO - 10.1016/j.freeradbiomed.2020.03.022
M3 - Journal article
C2 - 32304751
AN - SCOPUS:85083383472
VL - 153
SP - 12
EP - 16
JO - Free Radical Biology & Medicine
JF - Free Radical Biology & Medicine
SN - 0891-5849
ER -