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

4 ated form, perhydroxyl radical [(HO(2) (*)); pK(a) = 4.8], to T. cruzi at the phagosome compartment.

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

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

7 [pIC(50) (reporter gene) 8.76/7.08; pIC(50)/pK(b) (beta-arrestin2) 7.81/7.30].

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

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

10 A pK(a) of 5.45 for GSSH was determined, which is 3.49 uni

11 of 9.9 +/- 0.1 (k'(cat) = 24 +/- 2 s(-1)), a pK (E1) of 5.4 +/- 0.3, and a pK (E2) of 9.5 +/- 0.1 (k'

12 se data yielded a pK (ES1) of 5.4 +/- 0.2, a pK (ES2) of 9.9 +/- 0.1 (k'(cat) = 24 +/- 2 s(-1)), a pK

13 /- 2 s(-1)), a pK (E1) of 5.4 +/- 0.3, and a pK (E2) of 9.5 +/- 0.1 (k'(cat)/k' (m) = 220 +/- 10 s(-1

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

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

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

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

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

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

20 of Asp(22), with the latter now exhibiting a pK(a) of 6.4.

21 ns: 1) the efflux rate of WT LacY exhibits a pK(app) of ~7.2 that is unaffected by the imposed DeltaP

22 ion thermodynamics and avoids the need for a pK(a) scale in the solvent of interest.

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

24 bilized GlcP(Se) We found that Asp(22) has a pK(a) of 8.5 +/- 0.1, a value consistent with that deter

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

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

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

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

29 Ci1 retains a pK(a) of 7.6 so that both its protonated and deprotonate

30 (19)F NMR also revealed a pK(a) of 8.7 +/- 0.05 that we attributed to an active-si

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

32 When a pK(a)(LAC-MeCN) is less than zero for a given complex [M

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

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

35 h]quinoline is a superbasic compound, with a pK(aH) in acetonitrile greater than that of 1,8-bis(dime

36 ge 7.0-9.0, and fits of these data yielded a pK (ES1) of 5.4 +/- 0.2, a pK (ES2) of 9.9 +/- 0.1 (k'(c

37 2-(Trifluoromethyl)pyrrolidine (A14, pK(aH) 12.6) and the 2-imidazoliummethyl-substituted pyr

38 idazoliummethyl-substituted pyrrolidine A21 (pK(aH) 11.1) are outside the typical range for pyrrolidi

39 structure, fractional solvent accessibility, pK(a) of the conjugation site, surrounding residue's pI,

40 ll as other solution conditions such as acid pK(a), on the H(2)O(2)/H(2)O selectivity in electrocatal

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

42 d on a switchable fatty acid (hexanoic acid, pK(a) ~ 4.8).

43 HOSO displays an unforeseen strong acidity (pK(a) = -1) comparable with that of nitric acid and is f

44 assay to study the influence of the acidity (pK(a)) of heterocyclic leaving group of triazole urea de

45 bes (standards) for determining the acidity (pK(a)) of organic compounds in DMSO, which was achieved

46 (14d) combines nanomolar on-target activity (pK(i) = 8.5, pEC(50) = 9.5) with weak activity on cytoch

47 o[2.1.0]pentane did not significantly affect pK(a) of the corresponding derivatives and slightly incr

48 egative charge showed high M(2)R affinities (pK(i) (radioligand competition binding): 9.10-9.59).

49 a Y(4)R partial agonist with high affinity (pK(i) Y(4)R: 8.43).

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

51 rtial agonist with unchanged Y(4)R affinity (pK(i): 8.47).

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

53 osition, aminomethyl substituents with amine pK(a)'s > 7 accelerate, while those with pK(a)'s < 7 slo

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

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

56 By NMR, we analyzed pK(a) values for ionization of lead candidates, demonstr

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

58 rgy relationships between rate constants and pK(a) of the leaving group are curved upward, which is i

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

60 With the measured reduction potential and pK(a), the O-H bond dissociation free energy (BDFE) of h

61 eptide ligation in water: the reactivity and pK(aH) of alpha-aminonitriles makes them compatible with

62 are correlated with CXY stereochemistry and pK(a2-4) values for 13 CXY-bisphosphonic acids and imido

63 e effects of ionic strength on pH values and pK(a) values, on the selectivity, sensitivity, precision

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

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

66 of protonated LacY for sugar has an apparent pK (pK(app)) of ~10.5, due specifically to the pK(a) of

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

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

69 er the physiological range, but the apparent pK (pK(app)) for galactoside binding is 10.5.

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

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

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

73 bound O(2)-derived reduced species, such as pK(a), reduction potential, and BDFE; these may be relev

74 xploiting molecular characteristics, such as pK(a), we have been able to fine-tune our methodology to

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

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

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

78 The Bronsted basicities pK(aH) (i.e., pK(a) of the conjugate acids) of 32 pyrrol

79 ctivity within a range of measured basicity (pK(a) = 6.0-6.6) and lipophilicity (cLogD = 10-14).

80 ned rates have been related to the basicity (pK(aH) in water and K(b) in benzene) or nucleophilicity

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

82 ion the temperature dependence of pK(a)(CA), pK(a)(T) = -373.604 + 16,500/T + 56.478 ln T.

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

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

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

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

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

91 At physiological-like conditions pK(a)(CA) = 3.45 (I = 0.15 M, 37 degrees C), making CA s

92 The observed acidic constant (pK(a)) of these pH-dependent nanoswitches is linearly de

93 has a perturbed acid dissociation constant (pK(a)) compared with acyl-enzyme complexes with beta-lac

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

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

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

97 The proton-dissociation constants (pK(a)'s) of H19 in BM2 were found to be much lower than

98 Dissociation constants (pK(a)) and log P values were measured for the obtained c

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

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

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

102 Computationally derived pK(aH) values of quinolinoquinolines functionalized with

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

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

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

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

107 The Bronsted basicities pK(aH) (i.e., pK(a) of the conjugate acids) of 32 pyrrolidines and imi

108 le, intrinsic solubility, common-ion effect, pK(a), pH(max), and K(sp) values of three model compound

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

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

111 = 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(*-

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

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

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

115 amagnetic hydrides prepared in bulk all have pK(a)(LAC-MeCN) > 8.

116 hile the two other betaines and PFOAAmS have pK(a) values that are outside of the environmentally rel

117 Addition of acids having pK(a) values of >8.5 in CH(3)CN results in O-O bond homo

118 phosphomonoesters in their headgroups having pK(a) values in the physiological range.

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

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

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

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

123 troscopy (SEIRAS) demonstrates that the high pK(a) is due to Glu325 (helix X), which must be protonat

124 These high pK values are characteristic of the polyanionic peptides

125 ominant iodinating agent; nevertheless, HOI (pK(HOI) = 10.4) could not have produced this result, as

126 tional calculations of the aromatic hydrogen pK(a) values have helped us to rationalize the metalatio

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

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

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

130 M(-1) s(-1), respectively, and an identical pK(a) = 5.8 is obtained for both residues by NMR.

131 The degree of light-induced pK(a) change in the initiators correlates with the degre

132 t the effect of PS on the membrane insertion pK and lipid partitioning hinged on the sequence of the

133 icate that the effect of PS on the insertion pK does not merely depend on electrostatics, but it is m

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

135 nated in the In state due to a change in its pK(a) caused by cluster reduction, and (iii) Trp9 rotati

136 tially activates the substrate, lowering its pK(a) by 1.0 unit (DeltaG* = 1.4 kcal mol(-1)).

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

138 s in the immediate vicinity of Glu325 on its pK(a) The results are consistent with the idea that Arg3

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

140 properties and indicate that, given the low pK(a) of sulfonated- and hydroxy-sulfonated-PCBs, they p

141 ensitively detected than thiol ones (the low pK(a) of sulfonic acids facilitating their anionization

142 iol, a process likely facilitated by the low pK(a) of the leaving thiol MtAhpE-SH, highlighting the p

143 ripheral H27 is indeed the origin of the low pK(a)'s of H19 in wild-type BM2.

144 To determine if the lower pK(a)'s result from H27-facilitated proton dissociation

145 lidinones are significantly less basic (10 < pK(aH) < 12).

146 rrolidines have basicities in the range 16 < pK(aH) < 20, while imidazolidinones are significantly le

147 Further NMR analysis demonstrated Lys73 pK(a) to be ~5.2 to 5.6.

148 inated substrate analogs to directly measure pK(a) values and to monitor protein events in hydroxylas

149 back-titration method was applied to measure pK(a) values of two 1,3-dithiane-derived bissulfoxides a

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

151 riteria regarding lipophilicity and measured pK(a) in formulation are understood to have impacts on u

152 een the potential-dependence of the measured pK(a) and that calculated with electronic-structure calc

153 oth methods have been validated by measuring pK(a) values of compounds, for which values had been det

154 ,000-fold upon alkalinization of the milieu (pK(a) = 7.1).

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

156 tive metal with a sensitivity of 61 +/- 9 mV/pK(a) unit.

157 onstrate that the modulation of the observed pK(a) is due to a purely entropic contribution.

158 The experimentally obtained pK(aH) values of quinolino[7,8-h]quinoline derivatives s

159 cording to which, in the absence of acids of pK(a) <= 8, the intermediate diazonium ion resulting fro

160 , 5, 3, 2, which correspond to low bounds of pK(a) values of phenols, aliphatic, and aromatic carboxy

161 se free-energy surfaces with calculations of pK(a) for a number of potentially acidic protons in diff

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

163 high precision the temperature dependence of pK(a)(CA), pK(a)(T) = -373.604 + 16,500/T + 56.478 ln T.

164 ium mixture, leading to the determination of pK(a) = 28.8 for HP (THF, -80 degrees C).

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

166 Two methods for the determination of pK(a) values of weak acids are described, a direct titra

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

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

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

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

171 ering in acidity by a remarkable 11 units of pK(a).

172 tative mechanism of linker exchange based on pK(a) measurements, considerations of framework solubili

173 ules with high HSA binding affinity based on pK(a) shifts using UV-pH titration.

174 The optimal pK(a) values and structural preorganization endow H(2)BH

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

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

177 Pharmacokinetic (pK) data from an in vivo rat model showed the local tiss

178 he physiological range, but the apparent pK (pK(app)) for galactoside binding is 10.5.

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

180 rotonated LacY for sugar has an apparent pK (pK(app)) of ~10.5, due specifically to the pK(a) of Glu3

181 e, shape, electronic distribution, polarity, pK(a), dipole or polarizability, which can be either fav

182 However, predicted pK(a) and neutral permeabilities suggest that also the p

183 The physicochemical properties (pK(a) and log D) and hepatic stability of several AOXD d

184 -based binding at the NLuc-hH(3,4)Rs/mH(4)R [pK(d) 8.78/7.75/7.18, comparable to binding constants fr

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

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

187 y protonate bases with biologically-relevant pK(a)s and argue that CA has a previously unappreciated

188 absorption and the environmentally relevant pK(a).

189 ong range coulombic perturbations to residue pK(a) 's upon ET at copper, allowing SOD1's "electrostat

190 ate that the pK(a) of the catalytic residue (pK (ES1)) increases by 2 pH units in the His-257 mutants

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

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

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

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

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

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

197 HA, even though the substrates have the same pK(a)(C-H) values.

198 ng acidity enhancement equivalent to several pK(a) units.

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

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

201 cyclohexyl moiety in the 6-position, showed pK(i) values for mAChRs higher than those of 2 and a sel

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

203 ZrT/Irt-like protein (bbZIP), and in silico pK(a) calculations.

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

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

206 ength of the acid used as the proton source (pK(a) values ranging from 3.4 to 13.5 in DMF) and the ap

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

208 1.5 to pH 11.0 to examine the unfolded state pK(a) values and the pH dependence of protein stability

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

210 coefficients (P) and the weak acid strength (pK(a)-values) determine the dynamic behavior of the syst

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

212 The pK(a) involved in the Fe(II)-HNO Fe(II)-NO(-) + H(+) equ

213 The pK(a) of 3 was thus determined to be 24 +/- 0.6 in MeTHF

214 The pK(a) of the lone histidine residue in the peptide, whic

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

216 The pK(a)(LAC-MeCN)([MHL(n)](+)/ML(n)) of over 200 hydride c

217 The pK(a)(MeCN)([MHL(n)](+)/[ML(n)) of paramagnetic hydrides

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

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

220 w motion is most pronounced at and above the pK(a) of the histidines.

221 interface of these domains, and adjusts the pK(a) of SDHA(R451) so that covalent attachment of the f

222 charged residues in its vicinity affect the pK(a) of glucose/H(+) symport.

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

224 der rate constants for the reactions and the pK(a) values.

225 independent rate (k(1), rho = 0.65), and the pK(a)'s of the hydroxyl group of the carbinolamide (rho

226 constant of the first binding step below the pK(a) of the histidines, suggesting that ligand binding

227 a Hammett correlation was found between the pK(a) values of the complexes and the substituents on th

228 eficient auxiliary ligands decrease both the pK(a) of the Ni-bound amine and the barrier to reductive

229 , would change the microenvironment, but the pK(a) of Asp(22) corresponded to that of the WT.

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

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

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

233 Binding of DBA2+ to glucose changes the pK(a) of DBA2+ from 9.4 to 6.3, enabling opportunities f

234 benzoate 6-hydroxylase (3HB6H) depresses the pK(a) of the bound substrate analog 4-fluoro-3-hydroxybe

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

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

237 ctroscopy, thereby precisely determining the pK(a) of interest.

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

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

240 Moreover, it is shown how the pK(a) value can be determined based on titrations carrie

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

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

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

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

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

246 n electron-withdrawing group that lowers the pK(a) of the neighbouring boronic acid thereby facilitat

247 The presence of the fluorophore lowers the pK(a) of the side-chain guanidinium group by several ord

248 ally regulated pH sensing by maintaining the pK(a) values of triad residues within the physiologicall

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

250 ersatile strategy to rationally modulate the pK(a) of synthetic devices in a highly predictable and a

251 1.67 (+/-0.16), reaching a maximum near the pK(a) of HOBr.

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

253 roxylase (HPAH), revealing depression of the pK(a) of 3-fluoro-4-hydroxyphenylacetate by 2.5 pH units

254 y constitutes the first determination of the pK(a) of a biological persulfide and the first examinati

255 The rational regulation of the pK(a) of an ionizable group in a synthetic device could

256 t here a method for the determination of the pK(a) of histidine in complex or heterogeneous systems a

257 An investigation of the pK(a) values by changing the separation conditions in el

258 quantity via the potential-dependence of the pK(a).

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

260 The rate constants depend strongly on the pK(a) of the internal base, but depend much less on the

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

262 tion state stabilization and by reducing the pK(a) of the nucleophilic alcohol of a serine.

263 /Trp ring orientations while stabilizing the pK(a) of the primary proton acceptor D97 within the same

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

265 in BM2 were found to be much lower than the pK(a)'s of H37 in AM2.

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

267 ependence of ApbE activity indicate that the pK(a) of the catalytic residue (pK (ES1)) increases by 2

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

269 Similar to thioredoxins, the pK(a) between 7.5 and 8.1 that controls reactivity appea

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

271 (pK(app)) of ~10.5, due specifically to the pK(a) of Glu325, a residue that plays an irreplaceable r

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

273 nt (LAC) equation where contributions to the pK(a)(MeCN) from each ligand are simply added together,

274 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

275 (DFT) calculations are used to validate the pK(a)(LAC-MeCN) values of hydrides of W(III), Mn(II), Fe

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

277 of the inhibitors did not correlate with the pK(a) of the leaving group, whereas the position of the

278 in influenza A M2 tetramer determines their pK(a) values, which define pH-controlled proton conducti

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

280 ly lower than expected on the basis of their pK(a) values, and this may be due in part to the need fo

281 es as the proton acceptor, even though their pK(a) values are similar.

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

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

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

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

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

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

288 When pK(a)(LAC-MeCN) >> 0, the oxidation is reversible when t

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

290 However, the introduction of acids with pK(a) values of <8.5 elicits a different outcome, namely

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

292 to antagonism, giving Y(4)R antagonists with pK(i) values <=7.57.

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

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

295 Consistent with pK(a) measurements, the requirement for a strong base su

296 HPAH-C(2), respectively, are consistent with pK(a) tuning by one or more H-bonding interactions.

297 ntrolled singlet oxygen-generating dyes with pK(a) values in the physiological range were subsequentl

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

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

300 ine pK(a)'s > 7 accelerate, while those with pK(a)'s < 7 slow the rate of GSH addition at pH 7.4, rel