Stable thiyl radicals in dried yeast Cu(I)6-thionein.
It was of interest to obtain long-lived thiyl radicals embedded in organic matrices. Solid thiol compounds including penicillamine, glutathione, and cysteine were UV irradiated under anaerobic conditions at 293 K for 60 min. The formed radicals were identified by electron paramagnetic resonance (EPR) (g = 2.0265 +/- 0.0015) at 293 K as thiyl radicals. The blue-colored radical species were subjected to reflection spectrometry (lambda max = 601 +/- 3 nm). The color and the EPR signal remained unchanged for six months. At the same time, the UV irradiation of lyophilisized yeast Cu(I)6-thionein generated stable EPR detectable thiyl was seen when the Cu(I)-thiolate was used. No EPR detectable thiyl radicals radicals at a g-value of 2.026 +/- 0.001. Unlike irradiated cysteine, a five times higher concentration of thiyl radicals were measured in the Cu(I)-thiolates of penicillamine, glutathione, and thiophenole, indicating that the hexanuclear copper arrangement in Cu(I)-thionein is most suitable for both the formation and stabilization of this sulfur radical species.
Sievers
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Physiologisch-Chemisches Institut, Universität Tübingen, Germany.
Deters
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D
Hartmann
H J
HJ
Weser
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U
D002352:Carrier Proteins; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D005720:Gamma Rays; D008668:Metallothionein / Q000737:chemistry* / Q000528:radiation effects; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000528:radiation effects; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*; D013696:Temperature; D014466:Ultraviolet Rays
C500769:CUP1-1 protein, S cerevisiae; D002352:Carrier Proteins; D005609:Free Radicals; D013438:Sulfhydryl Compounds; C007121:copper thionein; D013455:Sulfur; D008668:Metallothionein