ライフサイエンスコーパス: pK

1 pK(a) values affect physicochemical properties such as a

2 pK(a) values can be obtained by measuring the pH respons

3 pK(a) values of indicators are determined from absorbanc

4 hexamethyldisilazane, HMDS, pK(Li) = 23.05, pK(Cs) = 29.26.

5 lective versus adenosine A(1); 14-16 from 1, pK(I) = 7.9-9.0, 19- to 59-fold selective).

6 he following values: pK(a1) = 8.14 +/- 0.15, pK(a2) = 7.54 +/- 0.15, k(f,min) = 18.1 +/- 1.3 s(-1), k

7 nity of TbbTIM for I(3-) at pH < 6 and an ~2 pK unit decrease in the basicity of the carboxylate side

8 d permit the bridging of a difference of >26 pK(a) units (in DMSO) between a propargylic hydrogen and

9 ot occur at pH 6.5 where boric acid (B(OH)3; pK(a) = 8.55) is the predominant species.

10 The His(33) pK(a) value, experimentally determined for the first tim

11 0.54 pK(i) units, and a median error of 0.34 pK(i) units.

12 y is estimated to yield a mean error of 0.44 pK(i) units, a standard deviation of 0.54 pK(i) units, a

13 and selective lead molecules (11-13 from 5, pK(I) = 7.5-8.5, 13- to >100-fold selective versus adeno

14 44 pK(i) units, a standard deviation of 0.54 pK(i) units, and a median error of 0.34 pK(i) units.

15 We report that there is a large ~6 pK unit increase in the basicity of the carboxylate side

16 orward by lowering the Ni(II)-S(H(+))-Cys(6) pK(a).

17 We calculate a pK(a) for PyH(0) of 31 indicating that PT preceding ET i

18 stant for hydroxide-catalyzed dehydration, a pK(a) of 30.8 +/- 0.5 was determined for formation of th

19 ay absorption spectroscopies, we determine a pK(a) value for this compound of 11.9.

20 Our platform determines a pK' value of 7.24 +/- 0.15, compared to 7.25 +/- 0.58 fo

21 Titration between pH 6.3 and 8.3 exhibited a pK of approximately 6.9.

22 e of two groups: a general base exhibiting a pK value of 4.5 and a general acid exhibiting a pK value

23 value of 4.5 and a general acid exhibiting a pK value of 7.8.

24 A transition-state analogue gave a pK(a) value of 6.27 +/- 0.05, which agrees strikingly we

25 quantum chemical calculations, Br-DMS has a pK(a) approximately 9.0 and thus remains partially depro

26 e contact with an ionizable group that has a pK(a) of approximately 6.7 when it is in complex with sk

27 ase, C75, serves as a general acid and has a pK(a) shifted toward neutrality.

28 This cysteine has been reported to have a pK(a) of 9.5 in the absence of substrate, decreasing to

29 Stopped-flow experiments indicate a pK(a) = 10.4 for DMS.

30 sents the first experimental assignment of a pK(a) value to a residue in a cytochrome P450.

31 pH dependency of the GOx redox potential, a pK(a) of 7.2 has been determined for the GOx flavohydroq

32 ld-type Fms1 and the H67A enzyme both show a pK(a) of about approximately 6.9; this suggests His67 is

33 Consequently, such a pK difference could have substantial ramifications for a

34 f silica, an archetype protic surface with a pK value similar to that of acidic amino acids.

35 ionization of an active site tyrosine with a pK(a) near 7 was included.

36 icate deprotonation of the counterion with a pK(a) of 6.3, which is also the pK(a) at which the M int

37 at catalysis by SsuD requires a group with a pK(a) of 6.6 +/- 0.2 to be deprotonated and a second gro

38 that PikDH2 has a key ionizable group with a pK(a) of 7.0 and can be irreversibly inactivated through

39 to be deprotonated and a second group with a pK(a) of 9.5 +/- 0.1 to be protonated.

40 activation of H(2)O oxidation occurs with a pK(a) of approximately 6.5, which could be a function of

41 33)P]-ATP revealed an ionizable group with a pK(a) value of ~7.5, which must be unprotonated for the

42 9)(4-) is a very strong Bronsted base with a pK(b) comparable to that of the NH(2)CH(2)CH(2)NH(-) ani

43 The availability of accurate pK(a) values for the folded state of HEWL and separate m

44 We also report the first carbon acid pK(a) values for proton transfer from C-6 of uridine (pK

45 data enabled the calculation of carbon acid pK(a) values in the range 16.5-18.5 for the 20 triazoliu

46 H2](+/0) couple is unaffected by weak acids (pK(a)(MeCN) = 15.3) but exhibits catalysis with HBF(4).E

47 ich compound 22 showed the highest affinity (pK(i) > 10) for the 5-HT(3) receptor.

48 t potent binder with low nanomolar affinity (pK(i) = 8.094 +/- 0.098).

49 70) and a 5-HT(1A) receptor partial agonist (pK(i) = 9.25, pD(2) = 9.03, E(max) = 47%, 5-HT(1A)/alpha

50 Two alternative "pK-matched" buffer systems were substituted for the trad

51 in binding energy (BE) of protonated amines, pK values of basic amino acids were calculated by plotti

52 and prior information that includes analyte pK(a), log P, acid/base type, and PSA are sufficient to

53 rmediate between pK(a)(H(3)O(+)) = -1.74 and pK(a)(H(2)O) = 15.7.

54 -parameter equation based on pK(a)(ArOH) and pK(a)(ArOSO2XH).

55 rmined the bond dissociation free energy and pK(a) of the new O-H bond in 6a to be 50.5 kcal/mol and

56 their basic properties, such as exposure and pK(a), to algorithms for functional prediction of differ

57 gated the relationship between (i)k(max) and pK(a) using four imidazole derivatives at three differen

58 correlation between estimates of antagonist pK(B), k(on), and k(off) from functional assays and thos

59 n (69), a highly potent oxytocin antagonist (pK(i) = 9.9) with >31000-fold selectivity over all three

60 nd interesting 5-HT(1A) receptor antagonist (pK(i) = 8.70) and a 5-HT(1A) receptor partial agonist (p

61 Apparent pK(a) values in sensor films derived from fluorescence d

62 is measured as a function of pH, an apparent pK (pK(app)) of approximately 10.5 is obtained.

63 blocked also by alkaline pH with an apparent pK value of approximately 8.7 for ClC-K1.

64 cleanly reversed with base, and an apparent pK(a) = 22.2 +/- 0.3 for the Cu2OOH unit in MeCN has bee

65 remains at a plateau, exhibiting an apparent pK(a) consistent with this nucleotide acting in general

66 ccumulates only at high pH, with an apparent pK(a) of 9, via deprotonation of a residue interacting w

67 ction is strongly pH dependent, and apparent pK(a) values were obtained for the first time for this c

68 entally observed ensemble dependent apparent pK(a)s and that the insight gained in the relatively sim

69 This, in turn, alters the dye's apparent pK(A) value.

70 In summary, we assign the apparent pK(a) of 8.2 observed for androstenedione binding to the

71 es to the experimentally observed "apparent" pK(a), obtaining a value of 6.5, in excellent agreement

72 (19) displayed high affinity for the A(3)AR (pK(D) = 9.36 +/- 0.12) and is >650-fold selective over o

73 instead of thermodynamic parameters such as pK(a) values, it is likely to describe only the electric

74 mics we found two distinct microscopic Asp30 pK(a)s: 8.5 in the closed structure and 4.3 in the open

75 on-state conformation that elevates the base pK(a) > 0.8 log unit relative to the precatalytic state.

76 SOM sorption for weak bases (pK(a) 4.5-7) was stronger at pH 4.5 than at pH 7, indica

77 ton transfer for reactants with higher basic pK(a) > ca. 2 (pKa of conjugate acid).

78 to induce PLD than the combined use of basic pK(a) and ClogP values.

79 ans-phase H-bonding for reactants with basic pK(a) < ca. -6 and to interfacial proton transfer for re

80 DeltaDeltaG(AM) (kJ/mol) together with basic pK(a) values to assign PLD inducing potential to a compo

81 bases with pK(a) values intermediate between pK(a)(H(3)O(+)) = -1.74 and pK(a)(H(2)O) = 15.7.

82 to clarify how the (i)k(max) is affected by pK(a).

83 which showed noticeably different calculated pK a values in the helix and strand conformations, appea

84 The calculated pK(a) values of catalytic residues confirm their propose

85 d protonation states based on the calculated pK(a) values suggest that pH affects the flexibility of

86 We tested the technique by calculating pK(a) values for 264 residues from 34 proteins.

87 environmental conditions, failed to capture pK(a) shifts.

88 In the first case, pK and/or KD(Na) are altered, and in the second case, th

89 In contrast, catalyst pK(a) values are a poor measure of reactivity, although

90 he importance of atmospheric pH and chemical pK(a) values in determining gas-particle partitioning of

91 ange, which often results in the chromophore pK values being shifted into the physiological range.

92 Our approach combines pK(a) (logarithmic acid dissociation constant) calculati

93 the 3-isobutyl group gave potent compounds (pK(i) > 9.0) with good aqueous solubility.

94 ed by literature precedent and computational pK(a) prediction were unable to quantitatively account f

95 ipophilicity (log P), dissociation constant (pK(a)), and polar surface area (PSA), on the intercompou

96 use the apparent acid dissociation constant, pK', as a proxy for intersystem comparison.

97 roughput determination of acidity constants (pK(a)) regardless of aqueous solubility, number of pK(a)

98 ccount the calculated equilibrium constants (pK(T)) for all tautomeric reactions.

99 Ionisation constants (pK(a) values) are fundamental to the variability of the

100 shifts, and some J-couplings, yielded a COOH pK(a) of 3.0 +/- 0.1 in both anomers.

101 The proton affinities and the corresponding pK(a) values in acetonitrile of the new superbases are e

102 vely, which are close to their corresponding pK(a) values.

103 ferent "microscopic", conformation-dependent pK(a) values.

104 netic susceptibility tensor is pH dependent (pK(a) approximately 7) when a histidine residue is locat

105 roposed here for the first time to determine pK(a) values of chromogenic hydrophobic pH sensitive pro

106 fluorescence method can be used to determine pK(a)'s for ionization of both A and C and reveals that

107 is acidic, has an experimentally determined pK(a)* of 0.9 in dimethyl sulfoxide and an estimated pK(

108 The experimentally determined pK(a)-specific (i)k(max) values allowed us to derive a g

109 residues in PYP that exhibit very different pK(a) values depending on whether the phenolic side chai

110 termediates, and as a result yield different pK values.

111 Asp-48 and Asp-66 display pK(a) values of 2.9 and 3.1 in our analysis, thus repres

112 her support the conclusion that the distinct pK(a) values found in mutations of the same type, but ap

113 In turn, drug pK(a) could be determined by profiling log D changes dur

114 dicted to be extremely acidic in DMSO (i.e., pK(a) < 0).

115 agnitude more acidic than acetic acid (i.e., pK(a) = 11.4 vs 12.3).

116 The results are also compared with earlier pK(Li)s reported from equilibria with lithium amides in

117 l effects cause an increase in the effective pK(a) of 5-HO-OG, following an increasing trend from 5.7

118 These studies predicted an elevated pK(a) for Asp(309) and proposed that protonation of this

119 theory analysis indicates that this elevated pK(a) results in a >10,000-fold reduction in the rate co

120 f 0.9 in dimethyl sulfoxide and an estimated pK(a)* of -0.3 in water.

121 = 4.1 x 10(8) M(-1) * s(-1) and an estimated pK(a)* value of ~5 +/- 1 for the [(bpy)(2)Ru(a)(II)(L(*-

122 yl]-guanidine (tris-DMPG), whereas estimated pK(a) values in acetonitrile range between 29.5 and 33.2

123 They exhibit experimental pK(BH)(+) values in acetonitrile of 32.3 and 42.1, respe

124 uridine (pK(CH) = 28.8) and 5-fluorouridine (pK(CH) = 25.1) in aqueous solution.

125 imizing the solvation reference energies for pK(a) calculations, we employed a method that allowed si

126 as a function of pH, we determined the four pK(a) values of the His37 tetrad in the viral membrane.

127 lysis (log(V(max)/K(M)) versus leaving group pK(a) value) reveals beta(LG) = -0.86 +/- 0.23, consiste

128 Measurements showed a high pK value (>11) of stigmatellin in the QB pocket of the d

129 A high pK(a) of 18.8 +/- 1.8 and a low E(1/2) of -0.074 V vs Fc

130 on Glu37, which exhibits an anomalously high pK(a) value and is located within the hydrophobic dimer

131 ange as a consequence of the atypically high pK values of the phosphoserine and phosphothreonine resi

132 ving strong Asp(102)-His(57) H-bonds or high pK(a) values, but is compatible with mechanisms involvin

133 r a deprotonated base with a relatively high pK(a).

134 These high pK values are characteristic of the polyanionic peptides

135 For hexamethyldisilazane, HMDS, pK(Li) = 23.05, pK(Cs) = 29.26.

136 recent determination of an iron(IV)hydroxide pK(a) approximately 12 in the thiolate-ligated heme enzy

137 upper limit of 2.7 on the iron(IV)hydroxide pK(a) in myoglobin.

138 o provide insight into the iron(IV)hydroxide pK(a) of histidine ligated heme proteins, we have probed

139 omised apparently because of the decrease in pK(a) brought about by the fluorine atom, which affects

140 More specifically, the shifts in pK(a) correlate with the dipole moments of the zinc-boun

141 larization, which accounts for the shifts in pK(a).

142 sing empirical and thermodynamic integration pK(a) estimates, along with conventional molecular dynam

143 strength corrections, degree of ionization (pK), and ion solvation effects on mobility.

144 ested in eluent pH either above or below its pK(a), we demonstrated that the sorption affinity of (iv

145 2) was determined through measurement of its pK(a) and E(1/2) in THF solution.

146 an imidazole group differs depending on its pK(a), and no systematic study has been conducted to cla

147 conditions, with k(cat) exhibiting a kinetic pK(a) = 7.22.

148 The unusual kinetic pK(a) further suggested that PHD2 might function physiol

149 The method also captures large pK(a) shifts of lysine and some glutamate point mutation

150 d) delivery: The role of the ionizable lipid pK(a) in the in vivo delivery of siRNA by lipid nanopart

151 A tight correlation between the lipid pK(a) value and silencing of the mouse FVII gene (FVII E

152 e binding and activity are enhanced by a low pK(a) for the phenolic proton, increased hydrophobicity,

153 The advantage of such a low pK(a) is an acceleration of the photocycle and high pump

154 The low pK(a) value of Asp(102) would appear to be incompatible

155 dies, probably account for its unusually low pK(a) value through preferential stabilization of its an

156 boxylate (13)C signals to have unusually low pK(a) values: 2.0, 3.2, and 1.7 for Glu(129), Glu(174),

157 n (CEP) transfer has been observed when pH < pK(a)(TyrOH), which is pH-dependent but not first-order

158 agreement of the microscopic and macroscopic pK(a) values and the accompanying structural analysis su

159 ed Raman crystallography to directly measure pK(a) values for the Ade38 N1 imino group of a hairpin r

160 hatidylcholine bilayer membranes, we measure pK(a) values below 7.0.

161 account, we utilized experimentally measured pK(a) values in the native and unfolded states to calcul

162 ,000-fold upon alkalinization of the milieu (pK(a) = 7.1).

163 ded states are close to the amino acid model pK(a) values, thus reflecting the weak intramolecular in

164 isplaying the 2',4'-dichlorobiphenyl moiety (pK(i) = 6.930 +/- 0.021).

165 site and measured their respective Ade38 N1 pK(a) values.

166 e to that of a weakly acidic drug (naproxen; pK(a) = 4.15).

167 nesis experiments indicate that the observed pK(a) values reflect ionization of Asp-15 and Tyr-142, r

168 Consideration of pK(a) values in conjunction with other molecular propert

169 rapid, simple, and flexible determination of pK(a) values of pharmaceutical targets.

170 s under acidic conditions, with estimates of pK(a)(N1) = -0.2 to 0.5.

171 xpected for a diester with leaving groups of pK(a) 9.09.

172 The majority of pK(a) values in protein unfolded states are close to the

173 regardless of aqueous solubility, number of pK(a) values, or structure.

174 optimum for the repair follows the order of pK(a) values for protonation of the adduct, suggesting t

175 hat nearly any type of phenol, regardless of pK(a) value, can be released in neutral solutions withou

176 related by a two-parameter equation based on pK(a)(ArOH) and pK(a)(ArOSO2XH).

177 le and the effect of the organic modifier on pK.

178 ne (FVII ED(50) ) was found, with an optimal pK(a) range of 6.2-6.5.

179 s determining the extent of dissociation, or pK(a), of the zinc-bound water, we apply quantum chemist

180 Models based on K(OW) or pK(a) fail to explain differences in sorption affinity o

181 pH 7.5 and must have an unusually perturbed pK(a) (> 7.5) suggesting that the change at E71 is a str

182 easured as a function of pH, an apparent pK (pK(app)) of approximately 10.5 is obtained.

183 filling valences with hydrogens, predicting pK values for titratable amino acids, assigning predefin

184 and limited conformational sampling produces pK(a) values that will be useful when rapid estimation i

185 /pH profile of a weakly basic drug (quinine; pK(a) = 7.95) was sigmoidal with respect to -dF/M(w) val

186 The argument is based on the radical pK(a) ( approximately 4.5) that is much higher than that

187 ulse excitation show that the G(*+) radical (pK(a) = 3.9) can be observed only at low pH and is hydra

188 to augment ligand affinity for the receptor (pK(B)), intrinsic efficacy (tauB), and both binding (alp

189 inding that new analogues of 7a with reduced pK(a) due to substitution with an electron-withdrawing s

190 RMSD to 0.93 pH units but improved relative pK(a) predictions for proximal catalytic residues.

191 in a large proportion of histidine residues (pK(a) approximately 6) depends on the physiological pH e

192 The respective pK(a) values for A and B acids were determined experimen

193 in PyCOOH(0) formation, confirming PyH(0)'s pK(a) as irrelevant for predicting PT from PyH(0) to CO(

194 adduct and the effect of the boronic acid's pK(a)(B) on the stability constant of the adduct are dis

195 data allow one to predict an effective (s)(s)pK(a) of approximately 15.6 for the (s)(s)pK(a)(NH) of C

196 ith relative barriers dependent on the (s)(s)pK(a)(HOAr/HOR).

197 (s)pK(a) of approximately 15.6 for the (s)(s)pK(a)(NH) of Cu(II):bis(2-picolyl)amine.

198 l the mutant enzymes similarly show the same pK(a) as wild-type Fms1, about approximately 7.4; this p

199 K(Li) = 22.09, compared to the cesium scale, pK(Cs) = 28.60.

200 p-(methylamino)biphenyl, 1, on our Li scale, pK(Li) = 22.09, compared to the cesium scale, pK(Cs) = 2

201 sing this method, we identify highly shifted pK(a)'s of 7.6 for adenine in a DNA oligonucleotide and

202 ion of both A and C and reveals that shifted pK(a)'s are prevalent in DNA and RNA secondary and terti

203 al attributes that contribute to the shifted pK(a), we determined crystal structures of hairpin riboz

204 This significant pK drop (DeltapK > 3.5) decreased dramatically to (Delta

205 ion scheme as does any other acid of similar pK (e.g., acetic acid).

206 A single pK(a) can be determined in 2 min and a set of 20 measure

207 given imidazole group exhibiting a specific pK(a) at a specific temperature.

208 ins through the measurement of site-specific pK(a)s and tautomer populations.

209 f p-HOBDI-BF2 and p-HOPyDI:Zn (excited state pK(a)'s, solvatochromism, kinetics, and thermodynamics o

210 strong correlation between the folded state pK(a) values and the unfolded state pK(a) values of HEWL

211 f mutant-induced effects on the folded state pK(a) values, allows us to estimate the pK(a) values of

212 1.5 to pH 11.0 to examine the unfolded state pK(a) values and the pH dependence of protein stability

213 presenting the most depressed unfolded state pK(a) values observed to date.

214 ed state pK(a) values and the unfolded state pK(a) values of HEWL, thus suggesting that the unfolded

215 d of a nitro group, including its synthesis, pK(a), rates of acid-catalyzed epimerization, and enzyma

216 high acidity of the perfluoroalkyl TEFDDOLs (pK(a) in DMSO: tetrakis-CF(3), 5.7; tetrakis-C(2)F(5), 2

217 (cis) of 5.3 and 6, which is much lower than pK(trans) (>10).

218 The pK of p-(methylamino)biphenyl, 1, on our Li scale, pK(Li

219 The pK values for the Asp (3.1 and 2.4), His (6.7), and Lys

220 The pK(a) of an acyclic aliphatic heptaol ((HOCH(2)CH(2)CH(O

221 The pK(a) of Glu-19 is decreased when troponin C is bound to

222 The pK(a) value of aspartic acid in the catalytic triad of s

223 The pK(a) values of four chromoionophores were successfully

224 The pK(a) values of the free ligands and the affinity consta

225 The pK(a)'s of the Sp1-3 cysteines and histidines were deter

226 The pK(BH+) values were measured to be between 29.0 and 35.6

227 tions, L213Asp-L212Glu --> Ala-Ala (AA), the pK of stigmatellin dropped to 7.5 and 7.4, respectively,

228 mbrane dominated estrone retention above the pK(a).

229 erion with a pK(a) of 6.3, which is also the pK(a) at which the M intermediate is observed in the pho

230 s to the QB site with high affinity, and the pK value of its phenolic group monitors the local electr

231 in C is bound to skeletal troponin I and the pK(a) of His-130 is shifted upward.

232 pt for binding K(+) in en solutions, and the pK(a) of HSn(9)(3-) is similar to that of en (i.e., Sn(9

233 n the combination of the solution pH and the pK(a)'s of both ARS and the arylboronic acid.

234 Because the pK(a) value for galactoside binding is approximately 10.

235 e interactions were most important below the pK(a) of estrone, whereas charge repulsion between estro

236 The proton influx is likely caused by the pK(a) of E132 in GR, which is lower than that of other m

237 ly of each component is preprogrammed by the pK(a) of the gelator.

238 ta-based Monte Carlo method to calculate the pK(a) values of protein residues that commonly exhibit v

239 h pH-based replica exchange to determine the pK(a) values of titratable residues of a glycoside hydro

240 variants typically relies on determining the pK parameter, the pH midpoint of peptide insertion into

241 tate pK(a) values, allows us to estimate the pK(a) values of seven acidic residues in the unfolded st

242 must be protonated to bind galactoside (the pK for binding is approximately 10.5); (iii) galactoside

243 With X = H, the pK(a) for A and B acids were observed to be 7.6 and 11.6

244 tions are consistent with an increase in the pK(a) of the ferric-peroxo anion, which favors its proto

245 and 1.4 unit decreases, respectively, in the pK(a) of the side chain of the catalytic base Lys-93, sh

246 1+) was also reflected in a reduction in the pK(a) values of the histidines by 3.6 and 2.2 pH units,

247 rdination to iron is posited to increase the pK(a) (where K(a) is the acid dissociation constant) of

248 Increasing the pK(a) of the acyl-sulfonyl linker yielded incremental en

249 ng the synthesis of prodrugs, increasing the pK(a) of the acyl-sulfonyl moiety, modulation of the lip

250 Increasing the pK(a) value of the imino proton by reduction of its 5,6-

251 g that indeed the cofactor may influence the pK(a) of Glu83 through an electrostatic interaction.

252 interaction, which substantially lowers the pK(a) of Asp85 by stabilizing its deprotonated state.

253 K(+) ions modulate the pK(a) of sensing histidine side chains whose charge stat

254 1.67 (+/-0.16), reaching a maximum near the pK(a) of HOBr.

255 dissolved in solutions whose pH is near the pK(a) of the pendant acid or basic group and undergo an

256 Here we report that the value of the pK can be strongly dependent on the method used for its

257 retation of experimental measurements of the pK(a) is complicated by the coupling between pH, protona

258 dence study allowed the determination of the pK(a) of all protonable residues, including the cysteine

259 xplained by differences in the values of the pK(a) of the proton donor (His64) and acceptor (zinc-bou

260 His67 as being responsible for either of the pK(a) values.

261 orescent isomer of adenine, to report on the pK(a) of a nearby ionizing base both in DNA secondary st

262 nteraction with His-54 that should raise the pK(a) of His-54 and freeze the imidazole ring in the pla

263 mpounds at varying pH values were taken, the pK(a) values for both compounds were measured, and UV-vi

264 odel system of isolated RC revealed that the pK of stigmatellin was controlled overwhelmingly by elec

265 three independent methods, we show that the pK(a) of the active site cysteine of mouse methionine su

266 s in the nucleophilic histidine and that the pK(a) of this histidine is crucially dependent on the se

267 Thus, the pK(a) values for the thiol group of Cys(31) and Cys(34)

268 alf-maximal activation at pH 6, close to the pK(a) of histidine, implicating the three native His res

269 utral pH but releases at a pH similar to the pK(a) of the imidazole side chain of histidine residues.

270 en A and B acids increased to 4.7 units: the pK(a) values for A and B acids were determined as 6.7 an

271 In some fluorescent Arch variants, the pK(a) of the protonated Schiff-base linkage to retinal i

272 The primary mechanism by which the pK(a) is lowered is hydrogen bonding of the active site

273 or the wild-type enzyme, consistent with the pK(a) values arising from the amine substrate or product

274 Their pK(BH)+ values were determined by transprotonation exper

275 ractions with the protein environment, their pK(a)s can be shifted from their solution values and, if

276 in the bulk, indicating a decrease in their pK(a) at the surface, and implying an enhanced hydroxide

277 These pK(a) values, which were corroborated by (31)P NMR measu

278 sing the charge-state populations from these pK(a)'s, we obtained the relative conductance of the fiv

279 DTBA has thiol pK(a) values that are ~1 unit lower than those of DTT an

280 ild-type Fms1, about approximately 7.4; this pK(a) is assigned to the substrate N4.

281 phic separation of proteins, high-throughput pK(a) determinations, etc.

282 chain of Glu-167 at the EH*I(3-) complex, to pK(EHI) = 7.7.

283 ately 4 for the protonated free enzyme EH to pK(EHI) approximately 10 for the protonated enzyme-inhib

284 This can lead to pK(a) values that are very different from those in water

285 exist in RNA and DNA at neutral pH owing to pK(a) shifting.

286 L-103 do not form fibrils at pH 10 (tyrosine pK(a)).

287 the very acidic radical cation of tyrosine (pK(a) approximately -2).

288 The upper pK(a) value was not present in the pH profiles of k(cat)

289 ues for proton transfer from C-6 of uridine (pK(CH) = 28.8) and 5-fluorouridine (pK(CH) = 25.1) in aq

290 e constant, k(r), with the following values: pK(a1) = 8.14 +/- 0.15, pK(a2) = 7.54 +/- 0.15, k(f,min)

291 .5) that is much higher than that for water (pK(a)(H3O(+)) = 0), which thermodynamically disfavors a

292 Acids with pK(a) </= 12.7 protonate [Fe2(bdt)(CO)6](-) with bimolec

293 pimerizations are initiated with amines with pK(a) 7.4 or greater.

294 sorption coefficients for strong bases with pK(a) > 7 was small, within 0.3 log units.

295 low proton transfer for acids and bases with pK(a) values intermediate between pK(a)(H(3)O(+)) = -1.7

296 hat 5-carboxyl-2'-deoxycytidine ionizes with pK(a) values of 4.28 (N3) and 2.45 (carboxyl), confirmin

297 vity has a bell-shaped dependence on pH with pK(a) values of approximately 7.3 and 10.5.

298 bed by titration of a protonatable site with pK = 7.3.

299 is chromophore protonates in two steps, with pK(cis) of 5.3 and 6, which is much lower than pK(trans)

300 y with the monodeprotonated form of zeranol (pK(a) values of 8.44 and 11.42).