Spectroscopy and reactivity of a photogenerated tryptophan radical in a structurally defined protein environment.
Near-UV irradiation of structurally characterized [Re(I)(CO)3(1,10-phenanthroline)(Q107H)](W48F/Y72F/H83Q/Y108W)AzM(II) [Az = Pseudomonas aeruginosa azurin, M = Cu, Zn]/[Co(NH3)5Cl]Cl2 produces a tryptophan radical (W108*) with unprecedented kinetic stability. After rapid formation (k = 2.8 x 106 s-1), the radical persists for more than 5 h at room temperature in the folded ReAzM(II) structure. The absorption spectrum of ReAz(W108*)M(II) exhibits maxima at 512 and 536 nm. Oxidation of K4[Mo(CN)8] by ReAz(W108*)Zn(II) places the W108*/W108 reduction potential in the protein above 0.8 V vs NHE.
Miller
Jeremiah E
JE
Beckman Institute, California Institute of Technology, CA 91125, USA.
Grădinaru
Cristian
C
Crane
Brian R
BR
Di Bilio
Angel J
AJ
Wehbi
William A
WA
Un
Sun
S
Winkler
Jay R
JR
Gray
Harry B
HB
D001400:Azurin / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D010618:Phenanthrolines / Q000737:chemistry; D010777:Photochemistry; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000378:metabolism; D012211:Rhenium / Q000737:chemistry; D014364:Tryptophan / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D005609:Free Radicals; D010618:Phenanthrolines; D001400:Azurin; D012211:Rhenium; D003300:Copper; D014364:Tryptophan; D015032:Zinc