101
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Van Hecke K, Cardinaels T, Nockemann P, Jacobs J, Vanpraet L, Parac-Vogt TN, Van Deun R, Binnemans K, Van Meervelt L. Enantioselective Assembly of a Ruthenium(II) Polypyridyl Complex into a Double Helix. Angew Chem Int Ed Engl 2014; 53:8959-62. [PMID: 25044471 DOI: 10.1002/anie.201404496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 05/22/2014] [Indexed: 11/06/2022]
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102
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Stroobants K, Ho PH, Moelants E, Proost P, Parac-Vogt TN. Selective hydrolysis of hen egg white lysozyme at Asp-X peptide bonds promoted by oxomolybdate. J Inorg Biochem 2014; 136:73-80. [DOI: 10.1016/j.jinorgbio.2014.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/11/2014] [Accepted: 03/11/2014] [Indexed: 10/25/2022]
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103
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Stroobants K, Goovaerts V, Absillis G, Bruylants G, Moelants E, Proost P, Parac-Vogt TN. Molecular origin of the hydrolytic activity and fixed regioselectivity of a Zr(IV) -substituted polyoxotungstate as artificial protease. Chemistry 2014; 20:9567-77. [PMID: 24958622 DOI: 10.1002/chem.201402683] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Indexed: 01/07/2023]
Abstract
A multitechnique approach has been applied in order to identify the thermodynamic and kinetic parameters related to the regioselective hydrolysis of human serum albumin (HSA) promoted by the Wells-Dawson polyoxometalate (POM), K15 H[Zr(α2 -P2 W17 O61 )2 ]. Isothermal titration calorimetry (ITC) studies indicate that up to four POM molecules interact with HSA. While the first interaction site is characterized by a 1:1 binding and an affinity constant of 2×10(8) M(-1) , the three remaining sites are characterized by a lower global affinity constant of 7×10(5) M(-1) . The higher affinity constant at the first site is in accordance with a high quenching constant of 2.2×10(8) M(-1) obtained for fluorescence quenching of the Trp214 residue located in the only positively charged cleft of HSA, in the presence of K15 H[Zr(α2 -P2 W17 O61 )2 ]. In addition, Eu(III) luminescence experiments with an Eu(III) -substituted POM analogue have shown the replacement of water molecules in the first coordination sphere of Eu(III) due to binding of the metal ion to amino acid side chain residues of HSA. All three interaction studies are in accordance with a stronger POM dominated binding at the positive cleft on the one hand, and interaction mainly governed by metal anchoring at the three remaining positions, on the other hand. Hydrolysis experiments in the presence of K15 H[Zr(α2 -P2 W17 O61 )2 ] have demonstrated regioselective cleavage of HSA at the Arg114Leu115, Ala257Asp258, Lys313Asp314 or Cys392Glu393 peptide bonds. This is in agreement with the interaction studies as the Arg114Leu115 peptide bond is located in the positive cleft of HSA and the three remaining peptide bonds are each located near an upstream acidic residue, which can be expected to coordinate to the metal ion. A detailed kinetic study has evidenced the formation of additional fragments upon prolonged reaction times. Edman degradation of the additional reaction products has shown that these fragments result from further hydrolysis at the initially observed cleavage positions, indicating a fixed selectivity for K15 H[Zr(α2 -P2 W17 O61 )2 ].
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104
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Goovaerts V, Stroobants K, Absillis G, Parac-Vogt TN. Molecular interactions between serum albumin proteins and Keggin type polyoxometalates studied using luminescence spectroscopy. Phys Chem Chem Phys 2014; 15:18378-87. [PMID: 24064593 DOI: 10.1039/c3cp52848k] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The interaction between the plenary Keggin H3PW12O40, lacunary Keggin K7PW11O39 and the Eu(III)-substituted Keggin K4EuPW11O39 (Eu-Keggin) type polyoxometalates (POMs), and the proteins human and bovine serum albumin (HSA and BSA) was studied using steady state and time-resolved Eu(III) luminescence and tryptophan (Trp) fluorescence spectroscopy. The excitation spectrum of the Eu-Keggin POM is dominated by a ligand-to-metal charge transfer band at 291 nm. In the absence of proteins, the number of water molecules coordinated in the first coordination sphere of the Eu(III) center of Eu-Keggin was determined to be 4, indicating that Eu(III) occurs as a 1 : 1 isomer in solution. In the presence of HSA or BSA, the number of coordinated water molecules decreased to 0 and 1, respectively, suggesting interaction between the Eu-Keggin POM and the protein surface. As a result of this interaction, a five-fold increase of the hypersensitive (5)D0 → (7)F2 transition in the luminescence intensity was observed for the Eu-Keggin-HSA complex. The association constants were calculated to be 1.5 × 10(2) M(-1) and 2.0 × 10(3) M(-1) for the Eu-Keggin-HSA and Eu-Keggin-BSA complexes, respectively. Tryptophan fluorescence quenching studies were performed and the quenching constants were calculated using a Stern-Volmer analysis. The obtained values of the quenching constants were 6.1 × 10(4) M(-1) and 2.0 × 10(6) M(-1) for the Eu-Keggin-HSA and Eu-Keggin-BSA complexes, respectively. The surface map of both proteins shows that the cavity containing the tryptophan has a positive surface potential, providing a specific binding site at the surface of albumin proteins for the negatively charged POM.
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105
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Shestakova P, Absillis G, Martin-Martinez FJ, De Proft F, Willem R, Parac-Vogt TN. Back Cover: Integrating 31P DOSY NMR Spectroscopy and Molecular Mechanics as a Powerful Tool for Unraveling the Chemical Structures of Polyoxomolybdate-Based Amphiphilic Nanohybrids in Aqueous Solution (Chem. Eur. J. 18/2014). Chemistry 2014. [DOI: 10.1002/chem.201490074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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106
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Shestakova P, Absillis G, Martin-Martinez FJ, De Proft F, Willem R, Parac-Vogt TN. Integrating31P DOSY NMR Spectroscopy and Molecular Mechanics as a Powerful Tool for Unraveling the Chemical Structures of Polyoxomolybdate-Based Amphiphilic Nanohybrids in Aqueous Solution. Chemistry 2014; 20:5258-70. [DOI: 10.1002/chem.201304969] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Indexed: 02/02/2023]
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107
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Demeyer PJ, Vandendriessche S, Van Cleuvenbergen S, Carron S, Bogaerts K, Parac-Vogt TN, Verbiest T, Clays K. Sandwich approach toward inverse opals with linear and nonlinear optical functionalities. ACS APPLIED MATERIALS & INTERFACES 2014; 6:3870-3878. [PMID: 24559215 DOI: 10.1021/am4048464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Three-dimensionally ordered macroporous materials have unique structural and optical properties, making them useful for numerous applications in catalysis, membrane science, and optics. Accessible and economic fabrication of these materials is essential to fully explore the many possibilities that these materials present. A new templating method to fabricate three-dimensionally ordered macroporous materials without overlayers is presented. The resulting structures are freestanding inverse opals with large-area uniformity. The versatility and power of our fabrication method is demonstrated by synthesizing inverse opals displaying fluorescence, chirality, upconversion, second harmonic generation, and third harmonic generation. This economical and versatile fabrication method will facilitate research on inverse opals in general and on linear and nonlinear optical effects in 3D photonic crystals specifically. The relative ease of synthesis and wide variety of resulting materials will help the characterization and improvement of existing anomalous dispersion effects in these structures, while providing a platform for the discovery and demonstration of novel effects.
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108
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Mihaylov TT, Parac-Vogt TN, Pierloot K. A computational study of the glycylserine hydrolysis at physiological pH: a zwitterionic versus anionic mechanism. Org Biomol Chem 2014; 12:1395-404. [PMID: 24430931 DOI: 10.1039/c3ob42372g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hydrolysis of GlySer at physiological pH was investigated by modeling the most feasible reaction mechanisms in aqueous phase at the MP2/6-311+(2df,2p)//SMD-M06/6-311+(2df,2p) level of the theory. To refine the energies of the most relevant transition states along the reaction paths the cluster-continuum concept was adopted. The hydrolytic process could proceed through two competitive mechanisms involving either the zwitterionic or the anionic form of GlySer. The calculations suggest that at physiological pH the actual mechanism is most probably mixed, anionic-zwitterionic. In this reaction scheme the first stage of N→O acyl transfer involves the anionic form whereas the second stage, during which the resultant ester is hydrolyzed, most likely involves the zwitterionic ester form of GlySer. The energy requirement for the first reaction stage is estimated to be slightly lower than for the second one. The calculated activation parameters (e.g. ΔG(#) = 27.8 kcal mol(-1)) for the nucleophilic addition of a water molecule to the ester carbonyl group of the zwitterionic ester are in good agreement with the experimentally determined values at pD 7.4 (ΔG(#) = 28.7 kcal mol(-1)).
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109
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Stroobants K, Absillis G, Moelants E, Proost P, Parac-Vogt TN. Regioselective hydrolysis of human serum albumin by Zr(IV)-substituted polyoxotungstates at the interface of positively charged protein surface patches and negatively charged amino acid residues. Chemistry 2014; 20:3894-7. [PMID: 24596298 DOI: 10.1002/chem.201303622] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/20/2014] [Indexed: 12/17/2022]
Abstract
Complexes comprising the Lewis acidic Zr(IV) metal and protein binding polyoxotungstate ligands of Lindqvist-, Keggin- and Wells-Dawson-type were found to region selectively hydrolyze human serum albumin at four distinct positions. Higher reactivities were found for structures with higher polyoxometalate charges and the cleavage positions were found in protein regions of mixed charge. Both findings suggest an electrostatic nature of the observed reactivity.
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110
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Debroye E, Ceulemans M, Vander Elst L, Laurent S, Muller RN, Parac-Vogt TN. Controlled Synthesis of a Novel Heteropolymetallic Complex with Selectively Incorporated Lanthanide(III) Ions. Inorg Chem 2014; 53:1257-9. [DOI: 10.1021/ic402643a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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111
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Debroye E, Eliseeva SV, Laurent S, Vander Elst L, Muller RN, Parac-Vogt TN. Micellar self-assemblies of gadolinium(iii)/europium(iii) amphiphilic complexes as model contrast agents for bimodal imaging. Dalton Trans 2014; 43:3589-600. [DOI: 10.1039/c3dt52842a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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112
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Debroye E, Parac-Vogt TN. Towards polymetallic lanthanide complexes as dual contrast agents for magnetic resonance and optical imaging. Chem Soc Rev 2014; 43:8178-92. [DOI: 10.1039/c4cs00201f] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In the spotlight: polymetallic complexes permitting efficient sensitization of lanthanide luminescence and exhibiting favorable relaxometric properties.
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113
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Mihaylov TT, Parac-Vogt TN, Pierloot K. A Mechanistic Study of the Spontaneous Hydrolysis of Glycylserine as the Simplest Model for Protein Self-Cleavage. Chemistry 2013; 20:456-66. [DOI: 10.1002/chem.201303564] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Indexed: 11/05/2022]
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114
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Parac-Vogt TN, Binnemans K, Görller-Walrand C. Absolute configuration assignment of D3-symmetric lanthanide complexes based on circular dichroism induced by interaction with a chiral probe. Chemphyschem 2013; 2:767-9. [PMID: 23686930 DOI: 10.1002/1439-7641(20011217)2:12<767::aid-cphc767>3.0.co;2-e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Indexed: 11/10/2022]
Abstract
Chiroptical properties and absolute configuration have been correlated for a series of [Ln(oda)3](3-) complexes in aqueous solution (Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, or Tm; oda=2,2'-oxydiacetic acid). Addition of the chiral probe L-proline (L-Pro) to a series of the racemic complexes resulted in an excess of the Λ-enantiomer.
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115
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Stroobants K, Absillis G, Shestakova PS, Willem R, Parac-Vogt TN. Hydrolysis of Tetraglycine by a Zr(IV)-Substituted Wells–Dawson Polyoxotungstate Studied by Diffusion Ordered NMR Spectroscopy. J CLUST SCI 2013. [DOI: 10.1007/s10876-013-0664-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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116
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Debroye E, Laurent S, Vander Elst L, Muller RN, Parac-Vogt TN. Dysprosium Complexes and Their Micelles as Potential Bimodal Agents for Magnetic Resonance and Optical Imaging. Chemistry 2013; 19:16019-28. [DOI: 10.1002/chem.201302418] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Indexed: 12/30/2022]
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117
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Ly HGT, Absillis G, Bajpe SR, Martens JA, Parac-Vogt TN. Hydrolysis of Dipeptides Catalyzed by a Zirconium(IV)-Substituted Lindqvist Type Polyoxometalate. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300270] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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118
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Stroobants K, Moelants E, Ly HGT, Proost P, Bartik K, Parac-Vogt TN. Polyoxometalates as a Novel Class of Artificial Proteases: Selective Hydrolysis of Lysozyme under Physiological pH and Temperature Promoted by a Cerium(IV) Keggin-Type Polyoxometalate. Chemistry 2013; 19:2848-58. [DOI: 10.1002/chem.201203020] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/15/2012] [Indexed: 11/10/2022]
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119
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Vanhaecht S, Absillis G, Parac-Vogt TN. Amino acid side chain induced selectivity in the hydrolysis of peptides catalyzed by a Zr(iv)-substituted Wells–Dawson type polyoxometalate. Dalton Trans 2013; 42:15437-46. [DOI: 10.1039/c3dt51893k] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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120
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Ly HGT, Absillis G, Parac-Vogt TN. Amide bond hydrolysis in peptides and cyclic peptides catalyzed by a dimeric Zr(iv)-substituted Keggin type polyoxometalate. Dalton Trans 2013; 42:10929-38. [DOI: 10.1039/c3dt50705j] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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121
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Heylen S, Joos L, Parac-Vogt TN, Van Speybroeck V, Kirschhock CEA, Martens JA. Entropy-Driven Chemisorption of NO xon Phosphotungstic Acid. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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122
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Heylen S, Joos L, Parac-Vogt TN, Van Speybroeck V, Kirschhock CEA, Martens JA. Entropy-Driven Chemisorption of NOxon Phosphotungstic Acid. Angew Chem Int Ed Engl 2012; 51:11010-3. [DOI: 10.1002/anie.201205636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Indexed: 11/09/2022]
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123
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Absillis G, Parac-Vogt TN. Peptide bond hydrolysis catalyzed by the Wells-Dawson Zr(α2-P2W17O61)2 polyoxometalate. Inorg Chem 2012; 51:9902-10. [PMID: 22928475 DOI: 10.1021/ic301364n] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this paper we report the first example of peptide hydrolysis catalyzed by a polyoxometalate complex. A series of metal-substituted Wells-Dawson polyoxometalates were synthesized, and their hydrolytic activity toward the peptide bond in glycylglycine (GG) was examined. Among these, the Zr(IV)- and Hf(IV)-substituted ones were the most reactive. Detailed kinetic studies were performed with the Zr(IV)-substituted Wells-Dawson type polyoxometalate K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O which was shown to act as a catalyst for the hydrolysis of the peptide bond in GG. The speciation of K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O which is highly dependent on the pD, concentration, and temperature of the solution, was fully determined with the help of (31)P NMR spectroscopy and its influence on the GG hydrolysis rate was examined. The highest reaction rate (k(obs) = 9.2 (±0.2) × 10(-5) min(-1)) was observed at pD 5.0 and 60 °C. A 10-fold excess of GG was hydrolyzed in the presence of K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O proving the principles of catalysis. (13)C NMR data suggested the coordination of GG to the Zr(IV) center in K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O via its N-terminal amine group and amide carbonyl oxygen. These findings were confirmed by the inactivity of K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O toward the N-blocked analogue acetamidoglycylglycinate and the inhibitory effect of oxalic, malic, and citric acid. Triglycine, tetraglycine, and pentaglycine were also fully hydrolyzed in the presence of K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O yielding glycine as the final product of hydrolysis. K(15)H[Zr(α(2)-P(2)W(17)O(61))(2)]·25H(2)O also exhibited hydrolytic activity toward a series of other dipeptides.
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124
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Ho PH, Mihaylov T, Pierloot K, Parac-Vogt TN. Hydrolytic Activity of Vanadate toward Serine-Containing Peptides Studied by Kinetic Experiments and DFT Theory. Inorg Chem 2012; 51:8848-59. [DOI: 10.1021/ic300761g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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125
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Dehaen G, Eliseeva SV, Verwilst P, Laurent S, Vander Elst L, Muller RN, De Borggraeve W, Binnemans K, Parac-Vogt TN. Tetranuclear d-f Metallostars: Synthesis, Relaxometric, and Luminescent Properties. Inorg Chem 2012; 51:8775-83. [DOI: 10.1021/ic300537y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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126
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Verwilst P, Eliseeva SV, Vander Elst L, Burtea C, Laurent S, Petoud S, Muller RN, Parac-Vogt TN, De Borggraeve WM. A Tripodal Ruthenium–Gadolinium Metallostar as a Potential αvβ3 Integrin Specific Bimodal Imaging Contrast Agent. Inorg Chem 2012; 51:6405-11. [DOI: 10.1021/ic300717m] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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127
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Vanhaecht S, Absillis G, Parac-Vogt TN. Hydrolysis of DNA model substrates catalyzed by metal-substituted Wells–Dawson polyoxometalates. Dalton Trans 2012; 41:10028-34. [DOI: 10.1039/c2dt30588g] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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128
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Debroye E, Dehaen G, Eliseeva SV, Laurent S, Vander Elst L, Muller RN, Binnemans K, Parac-Vogt TN. A new metallostar complex based on an aluminum(iii) 8-hydroxyquinoline core as a potential bimodal contrast agent. Dalton Trans 2012; 41:10549-56. [DOI: 10.1039/c2dt30605k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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129
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Dehaen G, Eliseeva SV, Kimpe K, Laurent S, Vander Elst L, Muller RN, Dehaen W, Binnemans K, Parac-Vogt TN. A Self-Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent. Chemistry 2011; 18:293-302. [DOI: 10.1002/chem.201101413] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/23/2011] [Indexed: 11/06/2022]
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130
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Ho PH, Stroobants K, Parac-Vogt TN. Hydrolysis of Serine-Containing Peptides at Neutral pH Promoted by [MoO4]2– Oxyanion. Inorg Chem 2011; 50:12025-33. [DOI: 10.1021/ic2015034] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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131
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Absillis G, Van Deun R, Parac-Vogt TN. Polyoxomolybdate Promoted Hydrolysis of a DNA-Model Phosphoester Studied by NMR and EXAFS Spectroscopy. Inorg Chem 2011; 50:11552-60. [DOI: 10.1021/ic201498u] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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132
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Dehaen G, Verwilst P, Eliseeva SV, Laurent S, Vander Elst L, Muller RN, De Borggraeve WM, Binnemans K, Parac-Vogt TN. A Heterobimetallic Ruthenium–Gadolinium Complex as a Potential Agent for Bimodal Imaging. Inorg Chem 2011; 50:10005-14. [DOI: 10.1021/ic200726t] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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133
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Verwilst P, Eliseeva SV, Carron S, Vander Elst L, Burtea C, Dehaen G, Laurent S, Binnemans K, Muller RN, Parac-Vogt TN, De Borggraeve WM. A Modular Approach towards the Synthesis of Target-Specific MRI Contrast Agents. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201100575] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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134
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Lethesh KC, Van Hecke K, Van Meervelt L, Nockemann P, Kirchner B, Zahn S, Parac-Vogt TN, Dehaen W, Binnemans K. Nitrile-Functionalized Pyridinium, Pyrrolidinium, and Piperidinium Ionic Liquids. J Phys Chem B 2011; 115:8424-38. [DOI: 10.1021/jp2027675] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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135
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Ramadan AM, Calatayud Sala JM, Parac-Vogt TN. Trinuclear rare earth metal complexes based on 1,3,5-triamino-1,3,5-trideoxy-cis inositol as catalysts for the hydrolysis of phosphodiesters. Dalton Trans 2011; 40:1230-2. [DOI: 10.1039/c0dt01257b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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136
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Ho PH, Breynaert E, Kirschhock CEA, Parac-Vogt TN. Hydrolysis of carboxyesters promoted by vanadium(v) oxyanions. Dalton Trans 2011; 40:295-300. [DOI: 10.1039/c0dt00744g] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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137
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Bajpe SR, Kirschhock CE, Aerts A, Breynaert E, Absillis G, Parac-Vogt TN, Giebeler L, Martens JA. Direct Observation of Molecular-Level Template Action Leading to Self-Assembly of a Porous Framework. Chemistry 2010; 16:3926-32. [DOI: 10.1002/chem.200903239] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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138
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Mamedov I, Parac-Vogt TN, Logothetis NK, Angelovski G. Synthesis and characterization of dinuclear heterometallic lanthanide complexes exhibiting MRI and luminescence response. Dalton Trans 2010; 39:5721-7. [DOI: 10.1039/b925556g] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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139
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Steens N, Ramadan AM, Absillis G, Parac-Vogt TN. Hydrolytic cleavage of DNA-model substrates promoted by polyoxovanadates. Dalton Trans 2010:585-92. [DOI: 10.1039/b913471a] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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140
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Absillis G, Cartuyvels E, Van Deun R, Parac-Vogt TN. Hydrolytic cleavage of an RNA-model phosphodiester catalyzed by a highly negatively charged polyoxomolybdate [Mo7O24]6- cluster. J Am Chem Soc 2009; 130:17400-8. [PMID: 19053457 DOI: 10.1021/ja804823g] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrolysis of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP), a commonly used RNA model substrate, was examined in molybdate solutions by means of (1)H, (31)P, and (95)Mo NMR, Raman, and Mo K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. (1)H and (31)P NMR spectroscopy indicate that at 50 degrees C and pD 5.9 the cleavage of the phosphodiester bond in HPNP proceeds with a rate constant of 6.62 x 10(-6) s(-1), giving a cyclic phosphate ester and p-nitrophenol as the only products of hydrolysis. The NMR spectra did not show evidence of any paramagnetic species, excluding the possibility of Mo(VI) reduction to Mo(V), and indicating that the cleavage of the phosphodiester bond is purely hydrolytic. The Mo K-edge XANES region also did not show any sign of Mo(VI) to Mo(V) reduction during the hydrolytic reaction. The pD dependence of k(obs) exhibits a bell-shaped profile, with the fastest cleavage observed at pD 5.9. Comparison of the rate profile with the concentration profile of polyoxomolybdates shows a striking overlap of the k(obs) profile with the concentration of heptamolybdate, suggesting that the highly negatively charged [Mo(7)O(24)](6-) is the hydrolytically active species. Kinetic experiments at pD 5.9 using a fixed amount of [Mo(7)O(24)](6-) and increasing amounts of HPNP revealed slight signs of curvature at 25 molar excess of HPNP. The data fit the general Michaelis-Menten reaction scheme, permitting the calculation of the catalytic rate constant k(2) (3.02 x 10(-4) s(-1)) and K(m) (1.06 M). Variable temperature (31)P NMR spectra of a reaction mixture revealed broadening of the HPNP (31)P resonance upon increase of temperature, implying the dynamic exchange process between free and bound HPNP at higher temperatures. Addition of salts resulted in the inhibition of HPNP hydrolysis, as well as addition of dimethyl phosphate, suggesting competition for the binding to [Mo(7)O(24)](6-). The hydrolysis of 10 equiv of HPNP could be achieved in the presence of 1 equiv of [Mo(7)O(24)](6-), and the multiple turnovers demonstrate that the reaction is catalytic. (31)P NMR and Mo K-edge EXAFS spectra measured during different stages of the hydrolysis indicated that under catalytic conditions a partial conversion of [Mo(7)O(24)](6-) into [P(2)Mo(5)O(23)](6-) occurs.
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141
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Deleersnyder K, Schaltin S, Fransaer J, Binnemans K, Parac-Vogt TN. Ceric ammonium nitrate (CAN) as oxidizing or nitrating reagent for organic reactions in ionic liquids. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.05.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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142
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Nockemann P, Binnemans K, Thijs B, Parac-Vogt TN, Merz K, Mudring AV, Menon PC, Rajesh RN, Cordoyiannis G, Thoen J, Leys J, Glorieux C. Temperature-Driven Mixing-Demixing Behavior of Binary Mixtures of the Ionic Liquid Choline Bis(trifluoromethylsulfonyl)imide and Water. J Phys Chem B 2009; 113:1429-37. [DOI: 10.1021/jp808993t] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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143
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Steens N, Ramadan AM, Parac-Vogt TN. When structural and electronic analogy leads to reactivity: the unprecedented phosphodiesterase activity of vanadates. Chem Commun (Camb) 2009:965-7. [DOI: 10.1039/b816785k] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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144
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Nockemann P, Thijs B, Parac-Vogt TN, Van Hecke K, Van Meervelt L, Tinant B, Hartenbach I, Schleid T, Ngan VT, Nguyen MT, Binnemans K. Carboxyl-Functionalized Task-Specific Ionic Liquids for Solubilizing Metal Oxides. Inorg Chem 2008; 47:9987-99. [DOI: 10.1021/ic801213z] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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145
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Cartuyvels E, Van Hecke K, Van Meervelt L, Görller-Walrand C, Parac-Vogt TN. Structural characterization and reactivity of gamma-octamolybdate functionalized by proline. J Inorg Biochem 2008; 102:1589-98. [PMID: 18374986 DOI: 10.1016/j.jinorgbio.2008.02.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 02/12/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
The reaction of molybdate and dl-proline at pH 3.4 results in the formation of a Na(4)[Mo(8)O(26)(proO)(2)] x 22H(2)O complex (pro=proline) in which two proline ligands are attached to molybdenum(VI) ions via monodentate coordination of the carboxylate groups. The structure of the complex was determined by single crystal X-ray diffraction and by combination of (1)H, (13)C and (95)Mo NMR spectroscopy techniques in solution. The structure of the complex is strongly dependent on the pH. At native pH 3.4 the octamolybdate-type structure seems to be present in solution, but the increase of pH to 5.8 resulted in a rearrangement of the structure to a heptamolybdate-type structure. At physiological pH, the polyoxometalate framework was completely dissociated into the monomeric MoO(4)(2-) unit. The reactivity of the Na(4)[Mo(8)O(26)(proO)(2)] x 22H(2)O towards the hydrolysis of ATP was tested at different pH values. While in solution at pH 3.4 the hydrolysis proceeded to yield AMP (adenosine monophosphate) and ADP (adenosine diphosphate) in nearly equal amounts, reaction mixture at pH 5.8 gave ADP as the only product of hydrolysis after 24h of reaction. At neutral pH, the hydrolysis of ATP was slower, but it proceeded to yield 75% of ADP after 48 h of reaction.
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Cartuyvels E, Absillis G, Parac-Vogt TN. Questioning the paradigm of metal complex promoted phosphodiester hydrolysis: [Mo7O24]6−polyoxometalate cluster as an unlikely catalyst for the hydrolysis of a DNA model substrate. Chem Commun (Camb) 2008:85-7. [DOI: 10.1039/b714860g] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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147
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Lokeren LV, Cartuyvels E, Absillis G, Willem R, Parac-Vogt TN. Phosphoesterase activity of polyoxomolybdates: diffusion ordered NMR spectroscopy as a tool for obtaining insights into the reactivity of polyoxometalate clusters. Chem Commun (Camb) 2008:2774-6. [DOI: 10.1039/b802671h] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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148
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Van Deun R, Nockemann P, Parac-Vogt TN, Van Hecke K, Van Meervelt L, Görller-Walrand C, Binnemans K. Near-infrared photoluminescence of lanthanide complexes containing the hemicyanine chromophore. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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149
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Laurent S, Parac-Vogt TN, Kimpe K, Thirifays C, Binnemans K, Muller RN, Vander Elst L. Bis(phenylethylamide) Derivatives of Gd-DTPA as Potential Receptor-Specific MRI Contrast Agents. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200601170] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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150
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Parac-Vogt TN, Kimpe K, Laurent S, Vander Elst L, Burtea C, Chen F, Muller RN, Ni Y, Verbruggen A, Binnemans K. Synthesis, characterization, and pharmacokinetic evaluation of a potential MRI contrast agent containing two paramagnetic centers with albumin binding affinity. Chemistry 2006; 11:3077-86. [PMID: 15776492 DOI: 10.1002/chem.200401207] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A dinuclear gadolinium(III) complex of an amphiphilic chelating ligand, containing two diethylenetriamine-N,N,N',N'',N''-pentaacetate (DTPA) moieties bridged by a bisindole derivative with three methoxy groups, has been synthesized and evaluated as a potential magnetic resonance imaging (MRI) contrast agent. Nuclear magnetic relaxation dispersion (NMRD) measurements indicate that at 20 MHz and 37 degrees C the dinuclear gadolinium(III) complex has a much higher relaxivity than [Gd(DTPA)] (6.8 vs 3.9 s(-1) mmol(-1)). The higher relaxivity of the dinuclear gadolinium(III) complex can be related to its reduced motion and larger rotational correlation time relative to [Gd(DTPA)]. In the presence of human serum albumin (HSA) the relaxivity value of the noncovalently bound dinuclear complex increases to 15.2 s(-1) per mmol of Gd3+, due to its relatively strong interaction with this protein. The fitted value of the binding constant to HSA (Ka) was found to be 10(4) M(-1). Because of its interaction with HSA, the dinuclear complex exhibits a longer elimination half-life from the plasma, and a better confinement to the vascular space compared to the commercially available [Gd(DTPA)] contrast agent. Transmetalation of the dinuclear gadolinium(III) complex by zinc(II) has been investigated. Biodistribution studies suggest that the complex is excreted by the renal pathway, and possibly by the hepatobiliary route. In vivo studies indicated that half of the normal dose of the gadolinium(III) complex enhanced the contrast in hepatic tissues around 40 % more effectively than [Gd(DTPA)]. The dinuclear gadolinium(III) complex was tested as a potential necrosis avid contrast agent (NACA), but despite the binding to HSA, it did not exhibit necrosis avidity, implying that binding to albumin is not a key parameter for necrosis-targeting properties.
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