TY - JOUR
T1 - Direct observation of a transient tyrosine radical competent for initiating turnover in a photochemical ribonucleotide reductase
AU - Reece, Steven Y.
AU - Seyedsayamdost, Mohammad R.
AU - Stubbe, Jo Anne
AU - Nocera, Daniel G.
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2007/11/14
Y1 - 2007/11/14
N2 - Photochemical ribonucleotide reductases (photoRNRs) are developed for the generation and transport of amino acid radicals by proton-coupled electron transfer (PCET) in this enzyme. The β2 subunit has been replaced with the [Re]-3,5-F2Y-R2C19 peptide, which substitutes 3,5-F2Y for Y at "position 356" and contains the Re(bpy)(CO)3CN ([Re]) photochemical radical generator. Excitation of this peptide with 355 nm light produces the [Re]0-3,5-F2Y· charge-separated state within the nanosecond laser pulse, as characterized by transient absorption (TA) spectroscopy. Excitation of the bound peptide:α2 complex results in 29% turnover after 10 min of photolysis, while the corresponding [Re]-Phe-R2C19:α2 system is inactive. The 3,5-F2Y· radical on the peptide bound to the Y731F-α2 variant has been observed by TA spectroscopy. These data allow us to observe, for the first time, a peptide-derived, protein-bound radical that is competent for initiating RNR turnover.
AB - Photochemical ribonucleotide reductases (photoRNRs) are developed for the generation and transport of amino acid radicals by proton-coupled electron transfer (PCET) in this enzyme. The β2 subunit has been replaced with the [Re]-3,5-F2Y-R2C19 peptide, which substitutes 3,5-F2Y for Y at "position 356" and contains the Re(bpy)(CO)3CN ([Re]) photochemical radical generator. Excitation of this peptide with 355 nm light produces the [Re]0-3,5-F2Y· charge-separated state within the nanosecond laser pulse, as characterized by transient absorption (TA) spectroscopy. Excitation of the bound peptide:α2 complex results in 29% turnover after 10 min of photolysis, while the corresponding [Re]-Phe-R2C19:α2 system is inactive. The 3,5-F2Y· radical on the peptide bound to the Y731F-α2 variant has been observed by TA spectroscopy. These data allow us to observe, for the first time, a peptide-derived, protein-bound radical that is competent for initiating RNR turnover.
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U2 - 10.1021/ja074452o
DO - 10.1021/ja074452o
M3 - Article
C2 - 17944464
AN - SCOPUS:36148975297
VL - 129
SP - 13828
EP - 13830
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 45
ER -