Tyrosine is a conserved redox-active amino acid that plays important roles in heme-copper oxidases (HCO). Despite the widely proposed mechanism that involves a tyrosyl radical, its direct observation under O2 reduction conditions remains elusive. Using a functional oxidase model in myoglobin called F33Y-CuBMb that contains an engineered tyrosine, we report herein direct observation of a tyrosyl radical during both reactions of H 2O2 with oxidized protein and O2 with reduced protein by electron paramagnetic resonance spectroscopy, providing a firm support for the tyrosyl radical in the HCO enzymatic mechanism.
ASJC Scopus subject areas
- Colloid and Surface Chemistry