ライフサイエンスコーパス: proton donor

1 sm where H2O, in addition to H+, serves as a proton donor.

2 gy to an extent dependent on the strength of proton donor.

3 consistent with water being the active site proton donor.

4 active-site histidine serving as the second proton donor.

5 -298 is correctly located to function as the proton donor.

6 or a conserved acidic residue that acts as a proton donor.

7 donor employed, and the concentration of the proton donor.

8 quantum calculations show it to be a potent proton donor.

9 ses it was beneficial to add an alcohol as a proton donor.

10 at D210 likely operates as the leaving group proton donor.

11 dard potential as dictated by the pKa of the proton donor.

12 a proton acceptor and, subsequently, Asp96 a proton donor.

13 ng into account the presence of an exogenous proton donor.

14 bstrate and that R67 DHFR does not possess a proton donor.

15 shed and this residue thereby becomes a good proton donor.

16 activation by acting as both an electron and proton donor.

17 d proton transfer, and the role of Tyr196 as proton donor.

18 posed to serve as a transiently deprotonated proton donor.

19 ing group, with a neutral Asp132 as a likely proton donor.

20 erring H(+) is initially associated with the proton donor.

21 Co(III)-hydride is formed by reaction with a proton donor.

22 m stabilization by solvent water acting as a proton donor.

23 postulated to adopt the role of active site proton donor.

24 ta2-N2) was also accomplished by addition of proton donors.

25 mer Bronsted bases blended with organic acid proton donors.

26 that were previously identified as possible proton donors.

27 cene and weak O-H bonds upon activation with proton donors.

28 H-bonding stabilizers and high-concentration proton donors.

29 vibronic coupling and its dependence on the proton donor-acceptor distance can significantly impact

30 ic coupling decreases exponentially with the proton donor-acceptor distance for the range of distance

31 To test the effect of varying the proton donor-acceptor distance in proton-coupled electro

32 r as the proton acceptor in part because the proton donor-acceptor distance is approximately 0.2 A sm

33 In this empirical model, the proton donor-acceptor distance is predicted to be larges

34 This dominant proton donor-acceptor distance is significantly smaller

35 ster than the first reaction since a smaller proton donor-acceptor distance leads to a larger overlap

36 del is not a good predictor of the effect of proton donor-acceptor distance on concerted-electron tra

37 alf arise from the change in the equilibrium proton donor-acceptor distance upon electron transfer.

38 isotope effect is strongly influenced by the proton donor-acceptor distance with the dominant contrib

39 ent-coupled dynamic networks to optimize the proton donor-acceptor distance, but evolutionary pressur

40 The decrease in proton donor-acceptor distances due to thermal fluctuati

41 e in a manner that decreases the equilibrium proton donor-acceptor distances or alters the molecular

42 kinetic isotope effect increases for larger proton donor-acceptor distances.

43 vibrational wave function overlap for larger proton donor-acceptor distances.

44 f the KIE is determined predominantly by the proton donor-acceptor frequency and the distance depende

45 e overall rate is strongly influenced by the proton donor-acceptor frequency, the vibronic coupling,

46 relation functions of the energy gap and the proton donor-acceptor mode, which can be calculated from

47 bond, which corresponds to a high-frequency proton donor-acceptor motion, and small inner-sphere and

48 s and is not significantly influenced by the proton donor-acceptor motion.

49 the dominance of the local component of the proton donor-acceptor motion.

50 n, as well as the solvent reorganization and proton donor-acceptor motion.

51 functions and the incorporation of multiple proton donor-acceptor motions.

52 eplacements, these substitutions perturb the proton donor-acceptor relative orientation change and th

53 cal and quantum mechanical treatments of the proton donor-acceptor vibrational motion are presented.

54 Thus, the proton donor-acceptor vibrational motion plays a vital r

55 sists of an aspartate residue serving as key proton donor/acceptor (Asp-684) and an arginine residue

56 ding to mutagenesis experiments, the role of proton donor/acceptor along the D-pathway is carried by

57 e pathway, in close proximity to the central proton donor/acceptor Asp-684.

58 atalytic role in both partial reactions as a proton donor/acceptor at the 3'-OH/3'-keto center.

59 y, site accessibility, and the presence of a proton donor/acceptor group near the reaction site, are

60 Activation by 4-MI as proton donor/acceptor in catalysis was determined in the

61 entation may play in its ability to act as a proton donor/acceptor in HCA II.

62 Histidine-86 has emerged as a potential proton donor/acceptor in the catalytic mechanism based o

63 These results directly establish E17 as a proton donor/acceptor in the Nia-S <--> Nia-C equilibriu

64 ding sites that include the proposed initial proton donor/acceptor of the K pathway, Glu-101 of subun

65 and the fully reduced FAD, functioning as a proton donor/acceptor to FAD.

66 nitiated by Lys 52 or Lys 410 as the primary proton donor/acceptor.

67 s for imidazole and derivatives as exogenous proton donors/acceptors in catalysis by HCA III.

68 rovide their carboxylic groups as substitute proton donors/acceptors in the absence of Glu-101II, as

69 la (H64A HCA II) can be rescued by exogenous proton donors/acceptors, usually derivatives of imidazol

70 The relationship between proton-donor affinity for Sm(II) ions and the reduction

71 osine can fulfill the role of an active site proton donor, albeit very poorly.

72 the desirable Pd(II)-precatalyst, (b) a soft proton donor and a bidentately coordinated dianionic lig

73 gen-bonding interactions and by bringing the proton donor and acceptor closer to each other with the

74 ed a role for phosphoric acid and acetate as proton donor and acceptor in the concerted electron-prot

75 ulated as a function of the distance between proton donor and acceptor nitrogen atoms.

76 intrinsically slow proton exchange between a proton donor and acceptor pair that are not in close con

77 h a hydrogen-bond relay inserted between the proton donor and acceptor sites was studied electrochemi

78 The electrolyte consists of a proton donor and acceptor slurry containing substituted

79 hich apparently hinder the close approach of proton donor and acceptor that facilitates MS-CPET.

80 ns in the catalytic cycle, namely first as a proton donor and later as the substrate in the reaction

81 idic side chains that could serve as general proton donor and nucleophile/base in a canonical hydroly

82 attraction between the dipole moments of the proton donor and proton acceptor must be balanced by the

83 The asymmetry in angular rigidity of the proton donor and proton acceptor of hydrogen-bonded hydr

84 nzoate or p-aminobenzoate, reveal a chain of proton donors and acceptors (the hydroxyl groups of Tyr2

85 f CO2(*-), which can dimerize and react with proton donors and even mild oxidants.

86 t with the shifts observed in other H-bonded proton donors and provides corroborating spectral eviden

87 Transfer of water between the chain of proton donors and the solvent also appears to be an esse

88 the NH amide proton of the upper side chain (proton donor) and glycine acetamide of the lower side ch

89 H(3)(+) is a strong acid (proton donor) and initiates chains of ion-molecule react

90 d Glu359 may function as the catalytic acid (proton donor) and nucleophile (base), respectively, duri

91 hange in distance between the phenol oxygen (proton donor) and quinoline nitrogen (proton acceptor),

92 In the absence of a proton donor (as occurs in H84N), the normal reaction pa

93 wering the pKa of asp-96, so as to make it a proton donor, as the third phase.

94 n acceptor rather than being the anticipated proton donor, as would be expected if Asp beta99 were io

95 dopsin photocycle is greatly slowed when the proton donor Asp-96 is removed with site-specific mutage

96 ules located between the Schiff base and the proton donor Asp96 in the cytoplasmic region.

97 tending from the Schiff base to the internal proton donor Asp96, stabilizes L and affects the L-to-M

98 llus stearothermophilus, considered possible proton donors at the active site, was carried out.

99 ton transfer into the RC, acting as RC-bound proton donors at the entrance of the proton-transfer pat

100 nvolving nitrogen, sulfur, and phosphorus as proton-donor atoms.

101 Lysine 230 was suggested to act as proton donor based on geometry and spatial proximity to

102 center or the absence of a lone pair on the proton donor, because F(3)Si-H.OH(2), F(2)NH.FH, F(2)PH.

103 ates through protonation implicating another proton donor besides E241.

104 47 or Lys48, functions as a rate-determining proton donor between pH 6 and pH 8.

105 Proton donors bound at the less flexible side chain of T

106 -O bond in 2 in the presence of electron and proton donors by a proton-coupled electron-transfer (PCE

107 The pigment lacks the proton donor carboxylate residue in helix C conserved in

108 anced monomer stability, lowering the pKa of proton donor catalytic residue, optimized spatial distri

109 hancement of catalytic activity by exogenous proton donors containing imidazole rings.

110 d ribonuclease cleavage mechanisms where the proton donor coordinates with the oxygen of the leaving

111 is of a judicious choice of a Sm(II) complex/proton donor couple, even in the presence of extremely s

112 circumvents a requirement for expulsion by a proton donor during attack by cysteine on the gamma phos

113 served Tyr that is proposed to function as a proton donor during reductive dehalogenation.

114 y been proposed to play a critical role as a proton donor during the second half-reaction of MurB, na

115 These results suggest that there are two proton donors during the activation of UV pigments, the

116 hat 2-e reduced forms develop H-bonding with proton donors (e.g., CH3OH) via the O-atom.

117 chiff base through a mutation of the primary proton donor (E108Q).

118 acid-base chemistry, we mutated the putative proton donor E17 to Q in the soluble hydrogenase I from

119 idues (H21G, E24D/G, and H116G), the general proton donor (E178A), and mutants designed to switch the

120 figuration of the diastereomer reacting, the proton donor employed, and the concentration of the prot

121 In K240M, the proton donor exchanges protons with the solvent at a hig

122 the 64 complexes in which these monomers are proton donors exhibit significant scatter.

123 d a glutamate at position 132 that acts as a proton donor for chromophore reprotonation during the ph

124 ning alcohol products by serving as a strong proton donor for electrochemical dehydration reductions.

125 n in the active site, cannot function as the proton donor for fumarate reduction.

126 e catalytic site and implicating His241 as a proton donor for leaving group activation.

127 ment Tyr 34 --> Phe suggest that Tyr 34 is a proton donor for O2* - reduction to H2O2 or is involved

128 e/bicarbonate exchanger), where it acts as a proton donor for the anion/proton cotransport function.

129 t a beta-hydroxylmethyl side chain acts as a proton donor for the binding of a novel ligand.

130 Glu(131) is a likely proton donor for the hydroxyl leaving group.

131 ore, we conclude that Glu46 functions as the proton donor for the protonation of pCA during the PYP p

132 Rather, H2O serves directly as the proton donor for the reaction.

133 otonated in pG and protonated in pB, but the proton donor for this process has not yet been identifie

134 r catalysis and may function indirectly as a proton donor for turnover, coupled to a protonation cycl

135 ed to twist into a conformation blocking the proton donor from its side, thus reversing the stereoche

136 However, bimolecular protonation by a proton donor from the bulk may be too slow to compete wi

137 ed by general acid/base (proton acceptor and proton donor) functionality, with nucleophilic addition

138 action, protonation of the substrate, by the proton donor glutamate.

139 However, the proton donor, glutamate 139 is also unexpectedly a membe

140 re attempted by the placement of a potential proton donor group at the active site.

141 een performed to decipher the influence of a proton-donor group on O-O bond activation.

142 However, molecules with strong proton donor groups, in particular, are tenaciously reta

143 s that hydrogen bonds from hydroxyl or other proton-donor groups to carbonyl oxygens potentially can

144 Chiral Bronsted acids (proton donors) have been shown to facilitate a broad ran

145 chain of hydrogen-bonded waters linking the proton donor His64 and acceptor zinc-bound hydroxide.

146 s64, yet the difference in p K a between the proton donor His64 and zinc-bound hydroxide was near zer

147 ifferences in the values of the pK(a) of the proton donor (His64) and acceptor (zinc-bound hydroxide)

148 esence of iron(II) shows a requirement for a proton donor, implying a role for an acidic group in the

149 he shift expected for tryptophan acting as a proton donor in a T-state hydrogen bond.

150 g evidence that Y171 does not operate as the proton donor in catalysis and that the additional role o

151 mutants indicate that Tyr425' is the primary proton donor in catalysis, with Tyr367' functioning as a

152 nd does not support the role of Asp 258 as a proton donor in catalysis.

153 he assignment of an arginine (Arg402) as the proton donor in fumarate reduction.

154 another aspartic acid residue functions as a proton donor in hydrolysis.

155 ition of exogenous imidazole which acts as a proton donor in place of the imidazole groups of His tha

156 ate that transiently protonated Lys47 is the proton donor in tetrahedral intermediate collapse to the

157 ce 2-enoyl-CoA, whereas Glu164 serves as the proton donor in the absence of Tyr166 to yield 3-enoyl-C

158 ncerted with proton transfer from an unknown proton donor in the active site.

159 xyl of Tyr34 is hydrogen bonded, acting as a proton donor in the active site.

160 acceptor in the hydration direction and the proton donor in the dehydration direction for the rate-l

161 pH and, therefore, is capable of acting as a proton donor in the enzyme-catalyzed reaction.

162 r studies suggested histidine as a potential proton donor in the hydrolysis of sucrose, but by mutage

163 rfaces and highlight the crucial role of the proton donor in the kinetics of electrocatalytic energy

164 oxylase activity and that Glu333 serves as a proton donor in the production of formate.

165 te that Y158 does not function formally as a proton donor in the reaction but likely functions as an

166 OD for DHO deuterated at the 5-position (the proton donor in the reaction).

167 catalytic residue, probably functioning as a proton donor in the reductive acylation of lipoamide on

168 Glu164 seems to function as proton donor in the Tyr166Phe mutant, because the Tyr166

169 r166 with the assistance of His252 acting as proton donor in the wild-type enzyme to produce 2-enoyl-

170 t an essential role of Glu202 as the initial proton donor in this isomerization reaction.

171 vor the epsilon-amino group of Lys166 as the proton donor in this step.

172 gher rate relative to turnover than does the proton donor in wild-type YPK.

173 s to the class of high-acidity excited-state proton donors in photochemistry and photobiology.

174 s to the class of high-acidity excited-state proton donors in photochemistry and photobiology.

175 equivalent efficiency of Glu64 and Asp64 as proton donors in the catalysis by CA III demonstrate a l

176 with the proposed roles of these residues as proton donors in the first step of catalysis.

177 are best to be avoided; (ii) the addition of proton donors in the form of protonated weak bases can b

178 ed by 4-methylimidazole (4-MI), an exogenous proton donor, in a saturable process with a maximum acti

179 First, ESR's proton donor is a lysine side chain that is situated ver

180 However, its role as a proton donor is still debated.

181 termolecular bending frequency of HF, as the proton donor, is linearly proportional to the square roo

182 This -SH group serves as a proton donor, is responsible for the biological activity

183 midazole groups of the His-H126 and His-H128 proton donors, located at the entrance of the transfer p

184 The mechanistic importance of HMPA and proton donors (methanol, 2-methyl-2-propanol, and 2,2,2-

185 alysis, which suggested that the presence of proton donors might further enhance rates.

186 If Lys166 indeed serves as the terminal proton donor, mutants lacking an ionizable side chain at

187 ow show that when alpha-195(His), a putative proton donor near the active site, is substituted by glu

188 Tr complex (revealed here) lacks any obvious proton donor near the N5 group.

189 as postulated that residue Cys-82 may be the proton donor of the decarboxylation reaction catalyzed b

190 that a proton-relay system is acting as the proton donor of the reaction (1).

191 on of CO(2) hydration at steady state and as proton donors of the exchange of (18)O between CO(2) and

192 of nonproductive binding sites for exogenous proton donors offers an explanation for the unusually lo

193 The effect of the proton donor on the kinetics of interfacial concerted pr

194 gesting the importance of lysine as either a proton donor or a stabilizing cation during strand cleav

195 lysis with a cytosine side chain acting as a proton donor or acceptor.

196 Instead, it acts as a viable proton donor past the rate-limiting step and a sluggish

197 of the excited state molecule occurs when a proton donor reacts with the carboxylate during the exci

198 d MR, suggesting that His-186 is not the key proton donor required for the reduction of 2-cyclohexen-

199 be inactive due to the loss of its putative proton donor residue, exhibited 27% of the wild-type act

200 Here, we mutagenized the predicted proton donor residues and the nucleophilic catalyst resi

201 rmed the catalytic function of the predicted proton donor residues, and sequence analysis suggested t

202 t Asp-97 and Glu-108 are proton acceptor and proton donor, respectively, in retinylidene Schiff base

203 These results demonstrate that proton donor structure strongly impacts the free energy

204 or even more efficient than widely employed proton donors such as ureas or dicarboxamides.

205 ue such as HisH(+) makes for a very powerful proton donor, such that even its CH..O H-bonds are stron

206 Acid-base reactions involving cyanide and proton donors, such as amino acids and other cell cultur

207 on structures and peptide domains, including proton donors, suggest that MGA and SI evolved by duplic

208 Trihydrogen-phosphate is a much better proton donor than dihydrogen- and monohydrogen-phosphate

209 A proton donor that complexes efficiently with SmI(2) must

210 al, and kinetic studies show that only those proton donors that coordinate or chelate strongly to Sm(

211 In the presence of strong proton donors the electrochemistry of the quinone become

212 In response to chemical substitutions of the proton donor, the energy of the transition state for dir

213 he proton acceptor Asp85 is connected to the proton donor, the retinal Schiff base, through a hydroge

214 By using strong (acidic) proton donors, the formal potential of the quinone redox

215 his pKa is likely to be that of the internal proton donor to Asp-194, the Glu-204 site, before photoe

216 er molecule in a water channel is the direct proton donor to enolpyruvate and that Thr-298 affects a

217 pH, affecting the protonation state of D396 (proton donor to FAD degrees (-)).

218 the pKa of aspartic acid D396, the putative proton donor to FAD.(-), from ~7.4 to >9, and favours a

219 led that, in addition to its function as the proton donor to fructose-6-phosphate during formation of

220 His(85) is a potential proton donor to reactive iron-oxo species during substra

221 The nature of the proton donor to the C-3 of the enolate of pyruvate, the

222 om the second monomer, is postulated to be 2 proton donor to the carbanion intermediate.

223 d that serine 229 was positioned to act as a proton donor to the developing C2 carbanion during the r

224 is that involves rate-limiting CPET from the proton donor to the electrode surface, allowing this cat

225 uestions on the role water plays as a direct proton donor to the iron-linked dioxygen.

226 y a hydroxide ion with H125 functioning as a proton donor to the leaving alcohol group.

227 ates that very unusually the N3 of A1 is the proton donor to the oxyanion leaving group.

228 The proposed role of H84 is as a proton donor to the oxyanion of the quinoid species such

229 with the presence of a hydrogen bond from a proton donor to the phenolic oxygen atom of a neutral ty

230 as OH..phi bonds formed by the approach of a proton donor to the pi electron cloud above the aromatic

231 l carboxyl group is in place of the internal proton donor to the retinal Schiff base in the light-dri

232 which substantiates its role as the internal proton donor to the retinal Schiff base.

233 on donors for reducing the catalyst and (ii) proton donors to activate the substrate via a proton-cou

234 h could lead to different accessibilities of proton donors to the binuclear center.

235 he Tyr and a conserved Asp are implicated as proton donors to the epoxide leaving group.

236 of glutamic acid 64 and aspartic acid 64 as proton donors to the zinc-bound hydroxide in a series of

237 oton acceptor (typically an enolate) and the proton donor (typically a thiol).

238 that the activation of H64W HCA II by these proton donors was reflected in the work functions w(r) a

239 In the presence of HMPA, the rate order of proton donors was zero and product studies showed that t

240 ed in a position to serve potentially as the proton donor, was mutated to cysteine.

241 henolate hydrogen bond and that Tyr16 is the proton donor when a bound naphtholate inhibitor is obser

242 lar protonation could be achieved by using a proton donor which complexes to SmI2, in which case the

243 e of the active site cavity, is the proposed proton donor which facilitates purine base departure.

244 dazole and pyridine derivatives as exogenous proton donors with the indole ring of Trp-64; these expe

245 ding the conserved catalytic nucleophile and proton donor, with endoglucanases from glucosyl hydrolas

246 p by NADH, assisted by Tyr(147) as catalytic proton donor, yields UDP-xylose adopting the relaxed (4)