ライフサイエンスコーパス: semiquinone

1 kedly less acidic, and stabilizes an anionic semiquinone.

2 nzyme has been demonstrated to stabilize the semiquinone.

3 duced, by a single electron transfer, to its semiquinone.

4 voids formation of the reactive intermediate semiquinone.

5 ing site for ubiquinol that stabilizes a ubi-semiquinone.

6 none-7 and that the enzyme stabilizes a mena-semiquinone.

7 interaction and the formation of the anionic semiquinone.

8 f the FMN or the accumulation of the anionic semiquinone.

9 tion competes with disproportionation of the semiquinone.

10 ilize significant amounts of the neutral FMN semiquinone.

11 action that oxidizes 4-methylcatechol to the semiquinone.

12 ogen bond donor to the methoxy oxygen of the semiquinone.

13 ges in the CW EPR signals of the cluster and semiquinone.

14 measure the association rate of the unstable semiquinone.

15 ducing a neutral quinone to a bound, anionic semiquinone.

16 at the Q(A) site may do the same for anionic semiquinone.

17 reduction of flavodoxin by NADH to the blue semiquinone.

18 eactivity of the nonfluorescent intermediate semiquinone.

19 ron-sulfur clusters, and a transiently bound semiquinone.

20 ncreased stabilization of both UQ-* and MQ-* semiquinones.

21 However, the o-semiquinone 1S generated by pulse radiolysis oxidation o

22 idpoint potentials are -114 mV (FMN oxidized/semiquinone), -212 mV (FMN semiquinone/hydroquinone), -2

23 w reduction potentials for both the oxidized/semiquinone (-301 mV) and semiquinone/hydroquinone coupl

24 The neutral imino-semiquinone, 4,6-di-tert-butyl-2-tert-butylimino-semiqui

25 ite to facilitate binding of half-protonated semiquinone - a reaction intermediate that is potentiall

26 reduction of the yellow quinone to the blue semiquinone, a second 1.4 times faster electron transfer

27 The observed superoxo:semiquinone-, alkylperoxo-, and product-bound intermedia

28 nd the other to the high-potential alpha-FAD semiquinone (alpha-FAD(*-)).

29 ke up one electron yielding a stable anionic semiquinone, alpha-FAD, which donates this electron furt

30 coupling of a cyanophthalide and a p-methoxy semiquinone aminal to forge the anthraquinone moiety of

31 ) based on fusion of cyanophthalides (V) and semiquinone aminals (VI, VII) under basic conditions are

32 n of the triplet diradical complex of flavin semiquinone and (*)OOH.

33 a rationale for stabilization of the anionic semiquinone and a remarkably low reduction potentials fo

34 rs an electron to the copper, giving radical semiquinone and Cu(I), the latter of which reduces O2 (p

35 flavin semiquinone; in contrast, the anionic semiquinone and hydroquinone species were observed with

36 n 19 and 135 ps, whereas the excited anionic semiquinone and hydroquinone states donate an electron t

37 D reduces cyt c at a higher rate in both the semiquinone and hydroquinone states.

38 behavior is consistent with that expected of semiquinone and hydroquinone-like moieties respectively.

39 generation of both an unstable neutral blue semiquinone and hydroquinone.

40 in other flavoproteins that form the anionic semiquinone and promote access of oxygen to N5.

41 Oxidation of semiquinone and reduction of cyt b or O(2) are subsequen

42 The quinone/semiquinone and semiquinone/hydroquinone midpoint potent

43 The generated radical intermediates, namely semiquinone and superoxide, are of great importance in r

44 The functional role of semiquinone and the EPR assignment of clusters N6a/N6b a

45 o the perturbed electron distribution in the semiquinone and the loss of enzymatic activity.

46 es from the oxidized form, to the more rigid semiquinone and to the much looser hydroquinone.

47 was reduced to its respective anionic flavin semiquinone and used for measuring inter-flavin distance

48 l revealed an intriguing interplay of flavin semiquinones and a protein conformational change that ga

49 teristics in comparison with H-bonds between semiquinones and Ndelta in other quinone-processing site

50 rm a redox cycle that continuously generates semiquinones and reduced haem, both of which react with

51 75, the FMN potentials are -103 mV (oxidized/semiquinone) and -175 mV (semiquinone/hydroquinone) at p

52 quinone/hydroquinone), -236 mV (FAD oxidized/semiquinone), and -264 mV (FAD semiquinone/hydroquinone)

53 forms of the oxidized, neutral, and anionic semiquinone, and anionic hydroquinone states.

54 the relative proportions of hydroxyquinone, semiquinone, and quinone species in the macromolecule.

55 x states--oxidized form, neutral and anionic semiquinones, and neutral and anionic fully reduced hydr

56 radical-producing step by time resolving the semiquinone anion (Anq*-), ketyl radical (*-BPA), and Y*

57 Semiquinone anion bands are resolved at approximately 14

58 ose to the Rieske protein, or if an unstable semiquinone anion intermediate diffuses rapidly to the v

59 f SP-AQH* or, for the other redox mediators, semiquinone anion-quinone electron exchange leading to n

60 of DHODB, small amounts of the neutral blue semiquinone are observed at approximately 630 nm, consis

61 This semiquinone arises, in part, by comproportionation betwe

62 75H mutant stabilizes an anionic form of the semiquinone as a result of the altered hydrogen bond net

63 inone as a single electron reductant, flavin semiquinone as the hydrogen atom source, and the enzyme

64 the presence of a short-lived anionic flavin semiquinone (ASQ) is not sufficient to infer the existen

65 Light reduces the dCRY FAD to an anionic semiquinone (ASQ) radical and increases CTT proteolytic

66 la CRY (dCRY) flavin cofactor to the anionic semiquinone (ASQ) restructures a C-terminal tail helix (

67 ich can be chemically reduced to the anionic semiquinone (ASQ).

68 med protonated superoxide and anionic flavin semiquinone at N5, before elimination of water affords t

69 revious pulsed EPR studies have shown that a semiquinone at the QH site formed during the catalytic c

70 The remaining non-stabilized neutral semiquinone, beta-FADH(*), immediately reduces ferredoxi

71 WT enzyme was green, due to air-stable FMN semiquinone (blue) and oxidized FAD (yellow).

72 ion of the isoalloxazine ring to the neutral semiquinone, both of which involve N5 protonation.

73 Semiquinone-bridged bisdithiazolyls 3 represent a new cl

74 n mixtures reveal trace amounts of a neutral semiquinone, but evidence for the presence of IPP-based

75 rations show that the protein stabilized the semiquinone by reducing the electrochemical midpoint pot

76 protons involved in hydrogen bonding to the semiquinone by substitution of 1H2O by 2H2O.

77 ng product, or it may be reduced back to the semiquinone by superoxide.

78 f direct one-electron oxidation of quinol to semiquinone by the Rieske protein.

79 Blue neutral FMN semiquinone can be readily observed; potentials of one e

80 ierpont's structurally characterized vanadyl semiquinone catecholate dimer complex, [VO(DBSQ)(DTBC)]2

81 from resonance Raman spectra to be a Cu(II)-semiquinone complex.

82 Using hypothetical Ga(3+)-catecholate/semiquinone complexes as references, 3,4-PCD-PCA was fou

83 uggesting that b(562) reduction also affects semiquinone concentration and superoxide production.

84 dioxygen, with the result that steady-state semiquinone concentrations in SRFA solutions are 2-3 ord

85 dized minus reduced difference spectrum of a semiquinone, consistent with charge recombination betwee

86 c-oxide synthase oxygenase FMN, FMN oxidized/semiquinone couple = +70 mV, FMN semiquinone/hydroquinon

87 The redox potential of the quinone/semiquinone couple of flavodoxin (Fld) is much higher th

88 Arg-alpha237 substantially destabilizes the semiquinone couple of the bound FAD and impedes electron

89 altered to a larger extent than the oxidized/semiquinone couple which is understood by a simple elect

90 is the position of the aminoquinol/Cu(II) to semiquinone/Cu(I) equilibrium on anaerobic reduction wit

91 increases the concentration of the cofactor semiquinone/Cu(I) following anaerobic reduction by subst

92 this study indicate that changes in cofactor semiquinone/Cu(I) levels are not sufficient to alter the

93 ubstrate, which varies from almost 0% to 40% semiquinone/Cu(I).

94 In addition, the electronic structure of the semiquinone cyt aa(3)-600 is more shifted toward the ani

95 rein that 1S and related 5,6-dihydroxyindole semiquinones decay mainly by a free radical coupling mec

96 As a rule, o-semiquinones decay through disproportionation leading to

97 he reoxidation process being rate limited by semiquinone deprotonation.

98 ate ubiquinone reductase activity and in ETF semiquinone disproportionation.

99 Thus, the slow semiquinone dissociation may not indicate significant th

100 ALR forms large amounts of neutral semiquinone during aerobic turnover with DTT.

101 dependent accumulation of the neutral flavin semiquinone during both the flavoenzyme reduction and re

102 idpoint reduction potentials of the oxidized/semiquinone (E(1)) and semiquinone/hydroquinone (E(2)) c

103 line widths of the neutral and anionic flavo-semiquinone EPR signals are unchanged from the wild-type

104 st, we find that upon excitation the anionic semiquinone (FAD(*-)) and hydroquinone (FADH(-)) have lo

105 state and photoreduced to the neutral flavin semiquinone (FADH degrees ) in its lit state.

106 FAD) in subpicosecond and of neutral radical semiquinone (FADH(*)) in tens of picoseconds through int

107 chrome b subunits minimizes the formation of semiquinone-ferrocytochrome b(H) complexes at center N a

108 cted functional signaling role for a neutral semiquinone flavin state (FADH(*)) for dCRY.

109 The directions of the TDMs in oxidized and semiquinone flavins were characterized decades ago, and

110 duction of FdsBG identified a neutral flavin semiquinone, FMNH(*), not previously observed to partici

111 Electron transfer from the TPQ semiquinone follows in the first irreversible step to fo

112 mescale of seconds: conformational gating of semiquinone for both forward and reverse electron transf

113 eotide (FAD) cofactor in its neutral radical semiquinone form (FADH(*)) results in the formation of F

114 rdIs, the B. anthracis NrdI is stable in its semiquinone form (NrdIsq) with a difference in electroch

115 significant fraction of NrdI resides in its semiquinone form in vivo, underscoring that NrdIsq is ca

116 binds tightly to and stabilizes the radical semiquinone form of 3,5-di-tert-butylcatechol.

117 Further, when the semiquinone form of ETF is used instead of the oxidized

118 ificantly stabilize the one-electron-reduced semiquinone form of FMN.

119 The anionic semiquinone form of the flavin, which is highly stabiliz

120 MADH to structurally imprint the as-purified semiquinone form of wild-type ETF and that the ability o

121 uinol form of reduced TPQ and TPQ(SQ) is the semiquinone form) occurs at a rate that could permit the

122 a copper-ligated cofactor proposed to be the semiquinone form.

123 line width was ~12 G, indicating its neutral semiquinone form.

124 ters in the [Fe(III)][FMNH(*)] (FMNH(*): FMN semiquinone) form of a human inducible NOS (iNOS) bidoma

125 nhibited by rotenone and likely derived from semiquinone formation at complex III.

126 The anionic semiquinone, formed by forward electron transfer at the

127 These results clearly indicate that the Q(B) semiquinone forms hydrogen bonds with two nitrogens and

128 ctures corresponding to the iminoquinone and semiquinone forms of the enzyme.

129 We found that this semiquinone forms through the transfer of one electron f

130 The one-electron reduced semiquinone forms transiently during the reaction, and t

131 d YkuP were expressed in their blue (neutral semiquinone) forms and reoxidized to the quinone form du

132 The FAD anionic semiquinone found in the crystals assumes a conformation

133 omproportionation to yield the corresponding semiquinone free radicals, as detected by electron param

134 eover, the capsule also protects the reduced semiquinone from protonation, thus transforming the role

135 ethyl and methoxy hyperfine couplings in the semiquinone generated in the three proteins indicated ab

136 e oxidized enzyme, whereas an anionic flavin-semiquinone has been reported in the reduced enzyme.

137 The neutral quinone and anionic semiquinone have similar affinities, which is required f

138 tials of the oxidized/semiquinone (E(1)) and semiquinone/hydroquinone (E(2)) couples for the FMN (E(1

139 P450, and the elevated potential of the FMN semiquinone/hydroquinone couple (-172 mV) is also an ada

140 MN oxidized/semiquinone couple = +70 mV, FMN semiquinone/hydroquinone couple = -180 mV, and heme = -1

141 The potentials of the semiquinone/hydroquinone couple of both FMN and FAD are

142 odoxin (Fld) is much higher than that of the semiquinone/hydroquinone couple.

143 both the oxidized/semiquinone (-301 mV) and semiquinone/hydroquinone couples (-464 mV).

144 The quinone/semiquinone and semiquinone/hydroquinone midpoint potentials (E(q/sq) an

145 The FMN semiquinone/hydroquinone redox couple was found to be si

146 -103 mV (oxidized/semiquinone) and -175 mV (semiquinone/hydroquinone) at pH 7.0 and 25 degrees C, an

147 mV (FMN oxidized/semiquinone), -212 mV (FMN semiquinone/hydroquinone), -236 mV (FAD oxidized/semiqui

148 (FAD oxidized/semiquinone), and -264 mV (FAD semiquinone/hydroquinone).

149 ochrome aa(3)-600 in comparison with the ubi-semiquinone in cytochrome bo(3).

150 volved in a hydrogen bond formation with the semiquinone in the high-affinity Q(H) site in the cytoch

151 te Q-reduction state because it comes from a semiquinone in the outer quinone-binding site in complex

152 reduction state of the Q pool, presumably a semiquinone in the Q-binding site (site I(Q)).

153 It explains the observed properties of the semiquinone in the Q-binding site, the rapid superoxide

154 flavor of V2 brand was remarkably similar to semiquinones in cigarette smoke with a higher g value (2

155 al signal in PM2.5 was remarkably similar to semiquinones in cigarette smoke.

156 emical exchange has been seen previously for semiquinones in ESR, but this is not possible for most c

157 quinone, with no stabilization of the flavin semiquinone; in contrast, the anionic semiquinone and hy

158 Superoxide oxidizes epinephrine to a semiquinone, initiating a series of reactions leading to

159 tron quinone redox chemistry that avoids the semiquinone intermediate altogether.

160 d electron-transfer mechanism, (2) a neutral semiquinone intermediate is formed in the biomimetic sys

161 t with an inner-sphere reaction of the Cu(I)-semiquinone intermediate with O(2) and are inconsistent

162 2) directly with the Cu(I) center of a Cu(I)-semiquinone intermediate.

163 uction, the isolated RnfG produces a neutral semiquinone intermediate.

164 d two-electron/two-proton transfer without a semiquinone intermediate.

165 inoquinol catalytic intermediate and a Cu(I)-semiquinone intermediate.

166 nsfer, avoiding formation of highly reactive semiquinone intermediates and producing quinols that pro

167 cal dianion species and the stability of the semiquinone intermediates during further reduction are d

168 Since semiquinone intermediates of quinol oxidation are genera

169 ine coupling of other protein nitrogens with semiquinone is <0.1 MHz.

170 The semiquinone is also formed in the D75E mutant, where the

171 The results support a model that the semiquinone is bound to the protein in a very asymmetric

172 tent with recently proposed models where the semiquinone is destabilized to limit superoxide producti

173 nd rearrangement of the oxidized dopamine, a semiquinone is formed.

174 n, limiting O(2) reduction; 2) the Q(o) site semiquinone is highly stabilized making it unreactive to

175 serve that, while the transient formation of semiquinone is not proton-coupled, the second eT process

176 The neutral form of this semiquinone is observed during reductive titration of IY

177 is for the air stability of the neutral blue semiquinone is protonation of the flavin N5 and strong H

178 The semiquinone is substoichiometric, even with conditions o

179 coupling of other protein nitrogens with the semiquinone is weak (<0.1 MHz).

180 -) = 2,5-dioxidobenzoquinone/1,2-dioxido-4,5-semiquinone), is shown to exhibit a conductivity of 0.16

181 quinone, 4,6-di-tert-butyl-2-tert-butylimino-semiquinone (isqH.), can be prepared by a conproportiona

182 The semiquinone-like organic species formed during photolysi

183 ived organic species, (ii) relatively stable semiquinone-like organic species, and (iii) hydroperoxy

184 ecause of the stabilization by anthocyanidin semiquinone-like resonance.

185 pecificity by raising barriers in defense of semiquinone loss or energy wasting short-circuit reactio

186 First, electrons from the ETF flavin semiquinone may enter the ETF-QO flavin one by one, foll

187 If a Cu(I)-TPQ semiquinone mechanism operates, then an alternative oute

188 are inconsistent with a sequential "movable semiquinone" mechanism but are consistent with a model i

189 e-binding pocket of complex II, and unstable semiquinone mediated by the Q cycle of complex III.

190 ity and reactivity of reaction intermediate, semiquinone, might require a cofactor that functions to

191 As a result, semiquinone moieties in SRFA play a much more important

192 mpound that possesses a Donor-Acceptor (D-A) SemiQuinone-NitronylNitroxide (SQNN) biradical ligand.

193 ause of flavin photoreduction to the neutral semiquinone (NSQ).

194 71 mV with two electrons, consistent with no semiquinone observed in the potential range studied, a r

195 The semiquinone of DeltaG141/E142N was slightly more stable

196 uclei similar to those recorded for the blue semiquinone of free flavins in aqueous solution, thus co

197 ael-type reaction, and radical coupling of a semiquinone of the formed dimer and a third caffeic acid

198 orientation, be it the sole identity of the semiquinone or not, blocks the oxygen-binding site, sugg

199 account for this behavior: 1) The Q(o) site semiquinone (or quinol-imidazolate complex) is unstable

200 st example of free radical dimerization of o-semiquinones outcompeting the classic disproportionation

201 decrease 1000-fold and the rate constant for semiquinone oxidation by b(566) to depend on the b(562)

202 s of reducing equivalents which results from semiquinone oxidation to quinone.

203 ted in a specific alteration of the rates of semiquinone oxidation.

204 transfer in photolyase, particularly for the semiquinone photoreduction process, which involves nearb

205 Moreover, semiquinones produced at the flavin site initiate redox

206 none redox couple, where ground-state flavin semiquinone provides the electron for substrate reductio

207 gen bonds to the two carbonyl oxygens of the semiquinone Q(A)(.-) in the reaction center (RC) from th

208 data allow the following conclusions: 1) The semiquinone, Q(B) (*-), is stabilized thermodynamically;

209 gen bonds to the two carbonyl oxygens of the semiquinone QA*- in the well-characterized reaction cent

210 een the OH group of Ser-L223 and the anionic semiquinone QB-*.

211 ndicate the reaction proceeds via the flavin semiquinone/quinone redox couple, where ground-state fla

212 The semiquinone/quinone reoxidation is found to exhibit slow

213 chain-propagating species, the deprotonated semiquinone radical (SQ(*) (-)) generated from both the

214 the formation of the protein tyrosine ortho-semiquinone radical (ToQ.).

215 a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA)

216 These states include the anionic semiquinone radical and fully reduced neutral and anioni

217 e low-energy (3)MLCT(SQ) state (Ru(III) phen-semiquinone radical anion) as the predominant nonradiati

218 mmogram, which leads to the formation of the semiquinone radical anions (P)-(+)-1(*-) and (M)-(-)-1(*

219 gher the steady-state level of the resulting semiquinone radical at near neutral pH.

220 We report the first direct detection of a semiquinone radical generated by the Q(o) site using con

221 A stable neutral flavin-semiquinone radical is observed in the air-oxidized enzy

222 A neutral flavin-semiquinone radical is observed in the oxidized enzyme,

223 uced forms exhibit neutral and anionic flavo-semiquinone radical signals, respectively, demonstrating

224 uggesting that Int-2 is a peroxo-Fe(III)-4NC semiquinone radical species.

225 eased amounts of reactive oxygen species and semiquinone radical, both of which can cause DNA damage,

226 adical, Ph = 1,4-phenylene, SQ = S = (1)/(2) semiquinone radical, Cat = S = 0 catecholate, and py = p

227 1 complex in the presence of an intermediate semiquinone radical, thus making the Qo-site a strong ca

228 ation methods gave rise to a transient DOPAL semiquinone radical, which was characterized by electron

229 tron out of the substrate to form a reactive semiquinone radical.

230 d a species with the optical properties of a semiquinone radical.

231 yrosyl radical in the formation of the ortho-semiquinone radical.

232 uced enzyme exhibits a stable anionic flavin-semiquinone radical.

233 -based reaction mechanism possibly involving semiquinone radical.

234 ] cluster and to FMN in the form of a flavin semiquinone radical.

235 ces Fe(III) in acidic conditions, generating semiquinone radicals (Q(*-)) that can oxidize Fe(II) bac

236 oth dihydroxy PCBs and PCB quinones can form semiquinone radicals (SQ(*-)) in vitro.

237 environments, we were able to stabilize two semiquinone radicals and thus observed their weak emissi

238 Reactive semiquinone radicals are quickly produced upon the encou

239 These semiquinone radicals are reactive intermediates that hav

240 However, the semiquinone radicals generated in pure hydroquinone solu

241 are rapidly oxidized by dioxygen, while the semiquinone radicals generated in SRFA solution are resi

242 e critical role of quinoid intermediates and semiquinone radicals in CL generation from polychlorinat

243 inoid intermediates, but more interestingly, semiquinone radicals were produced during the degradatio

244 of O2 due to further cycling between oxygen, semiquinone radicals, and iron species.

245 The generation of semiquinone radicals, superoxide, and hydroxyl radicals

246 ve proxies, which includes the generation of semiquinone radicals.

247 of adrenochrome increases if the epinephrine semiquinone reacts with O(2) to form more superoxide, bu

248 stabilized blue semiquinone with an oxidized/semiquinone reduction potential of -179 mV.

249 (14)N and (15)N HYSCORE spectra of the Q(B) semiquinone show the interaction with two nitrogens carr

250 More than 90% of the semiquinone signal originated from the single entity wit

251 The semiquinone signal(s) decreased by 60% when with asimici

252 Furthermore, we found small but significant semiquinone signal(s), which have been reported only for

253 For the FAD semiquinone, significantly different potentials were obt

254 of a spin interacting state between the FMN semiquinone species and the reduced 2Fe-2S center.

255 The semiquinone species disappeared upon full reduction and

256 ference in the steady-state concentration of semiquinone species has a dramatic effect on the cycling

257 Paramagnetic interactions show that the new semiquinone species is buried in the protein, probably i

258 on." It is believed that a strongly reducing semiquinone species is essential for this process, and i

259 the redistribution of charge density in the semiquinone species, or the altered hydrogen bonding net

260 tate ubiquinone (UQ) and its reduced anionic semiquinone (SQ(-)) from the Q(A) site.

261 trogens from residues R71 and H98 around the semiquinone (SQ) at the high-affinity Q(H) site.

262 cal ligands are composed of an S = 1/2 metal semiquinone (SQ) donor and an S = 1/2 nitronylnitroxide

263 acterize the exchangeable protons around the semiquinone (SQ) in the Q(A) and Q(B) sites, using sampl

264 The design of novel, functionalized semiquinone (SQ) ligands which combine structural rigidi

265 ully oxidized (ox), the one-electron reduced semiquinone (sq), or the two-electron fully reduced hydr

266 ter P by reducing quinone (Q) at center N to semiquinone (SQ), which is bound tightly.

267 oxidized quinone, (ii) one-electron reduced semiquinone (stable neutral species (blue) or unstable r

268 protein environment for Q(B) in its reduced semiquinone state and suggest that the conformational ch

269 the unusually high stability of the anionic semiquinone state in wETF.

270 mammalian cytochrome P450 reductase, the FMN semiquinone state is not thermodynamically stable and ap

271 gen bonds in the redox tuning of the primary semiquinone state of photosystem II.

272 f IPP-bound enzyme indicate that the neutral semiquinone state of the flavin is stabilized thermodyna

273 dating the tuning and control of the primary semiquinone state, Q(A)(-), of photosystem II.

274 PSAO) exists predominantly in the Cu(I), TPQ semiquinone state.

275 but to a much greater extent for the anionic semiquinone state.

276 ibution map in the isoallosazine ring in its semiquinone state.

277 ximately 110 mV between the hydroquinone and semiquinone state.

278 rmined that the excited neutral oxidized and semiquinone states absorb an electron from the adenine m

279 vin interactions of the oxidized and anionic semiquinone states of the electron-transfer flavoprotein

280 placements destabilize both the oxidized and semiquinone states of the flavin, but to a much greater

281 Raman bands in both the oxidized and anionic semiquinone states of the protein.

282 ilization of the one-electron-reduced flavin semiquinone that is differentially expressed in the nitr

283 barrier toward the reduction of the anionic semiquinone that is observed in the wild-type wETF was e

284 which is readily photoreduced to the anionic semiquinone through a set of 3 highly conserved Trp resi

285 ge in the radicals formed was observed--from semiquinone to chlorophenoxyl radicals.

286 delivery of a hydrogen atom from the flavin semiquinone to the prochiral radical formed after cycliz

287 ith g-value between 2.0029 and 2.0044, and a semiquinone-type radical, with g-value from 2.0050 to as

288 These radicals are similar to semiquinone-type, environmentally persistent free radica

289 and thermodynamic destabilization of the FAD semiquinone uncouples or limits electron transfer to an

290 Nonetheless, both DeltaGly-141 red semiquinones were less stable than those of the correspo

291 uced, and reduction of b(562) stabilized the semiquinone when b(566) was oxidized.

292 tein complex (CaCaMxFMN) forms an air-stable semiquinone when reduced with NADPH and reduces cytochro

293 Instead, O2 oxidizes the 4-methylcatechol semiquinone, which is formed by comproportionation of 4-

294 ggest that DNQ undergoes bioreduction to its semiquinone, which then is re-oxidized by molecular oxyg

295 reduced form of enzyme is an anionic flavin semiquinone, whose formation requires the substrate, but

296 eads to formation of an unstable red anionic semiquinone with a more negative potential than the hydr

297 The FMN formed a kinetically stabilized blue semiquinone with an oxidized/semiquinone reduction poten

298 differences in the interactions of the mena-semiquinone with cytochrome aa(3)-600 in comparison with

299 ed to study the interaction of the Q(B) site semiquinone with nitrogens from the local protein enviro

300 coupling, J) involving a spin SD = 1/2 metal semiquinone (Zn-SQ) donor and a spin S(A) = 1/2 nitronyl