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Jastrzab R, Nowak M, Zabiszak M, Odani A, Kaczmarek MT. Significance and properties of the complex formation of phosphate and polyphosphate groups in particles present in living cells. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.213810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ryan AL, Fitzgerald MC, Ozsváth A, Twamley B, Buglyó P, Murphy BM, Griffith DM. Ni(II), Pd(II), and Pt(II) Complexes of the Hedgehog Pathway Inhibitor GANT61-D. Inorg Chem 2019; 58:16075-16086. [PMID: 31729870 DOI: 10.1021/acs.inorgchem.9b02632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
GANT61-D is an important hedgehog pathway inhibitor and an interesting ligand candidate for metal coordination. The first examples of metal complexes of the potent hedgehog pathway inhibitor GANT61-D are described. The reaction of Ni(II), Pd(II), and Pt(II) precursors with the hedgehog pathway inhibitor GANT61-D gave [NiII(GANT61-D)(OH2)3(μ2-SO4)(μ3-SO4)] (1), [PdII(Cl)(GANT61-D)]Cl (2), [PtII(Cl)(GANT61-D)]Cl, and [PtII(CBDCA-2H)(GANT61-D)]. X-ray crystal structure analysis revealed that GANT61-D is a versatile N-donor ligand that can act as a bidentate ligand via the diaminopropane (DAP) N atoms or a tridentate ligand via the DAP N atoms and one dimethylaniline N atom. Protonation constants of the GANT61-D ligand in water and in a 60:40 (w/w) dimethyl sulfoxide-water solvent mixture were determined. Potentiometric and spectroscopic data on the NiII(GANT61-D) system indicate the formation of octahedral 1:1 species with medium stability in solution. 1 and 2 exhibited noteworthy in vitro cytotoxicity against medulloblastoma cancer cells.
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Affiliation(s)
- Aisling L Ryan
- Department of Chemistry , Royal College of Surgeons in Ireland , 123 St. Stephen's Green , Dublin D02 YN77 , Ireland
| | - Marie-Claire Fitzgerald
- Department of Physiology and Medical Physics , Royal College of Surgeons in Ireland , 31A York Street , Dublin D02 YN77 , Ireland.,National Children's Research Centre at the Children's Health Ireland at Crumlin , Dublin D12 N512 , Ireland
| | - András Ozsváth
- Department of Inorganic and Analytical Chemistry , University of Debrecen , Egyetem tér 1 , Debrecen H-4032 , Hungary
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin , University of Dublin , Dublin D02 PN40 , Ireland
| | - Péter Buglyó
- Department of Inorganic and Analytical Chemistry , University of Debrecen , Egyetem tér 1 , Debrecen H-4032 , Hungary
| | - Brona M Murphy
- Department of Physiology and Medical Physics , Royal College of Surgeons in Ireland , 31A York Street , Dublin D02 YN77 , Ireland.,National Children's Research Centre at the Children's Health Ireland at Crumlin , Dublin D12 N512 , Ireland
| | - Darren M Griffith
- Department of Chemistry , Royal College of Surgeons in Ireland , 123 St. Stephen's Green , Dublin D02 YN77 , Ireland
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Sayer AH, Blum E, Major DT, Vardi-Kilshtain A, Levi Hevroni B, Fischer B. Adenosine/guanosine-3',5'-bis-phosphates as biocompatible and selective Zn2+-ion chelators. Characterization and comparison with adenosine/guanosine-5'-di-phosphate. Dalton Trans 2016; 44:7305-17. [PMID: 25797179 DOI: 10.1039/c5dt00080g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although involved in various physiological functions, nucleoside bis-phosphate analogues and their metal-ion complexes have been scarcely studied. Hence, here, we explored the solution conformation of 2′-deoxyadenosine- and 2′-deoxyguanosine-3′,5′-bisphosphates, 3 and 4, d(pNp), as well as their Zn(2+)/Mg(2+) binding sites and binding-modes (i.e. inner- vs. outer-sphere coordination), acidity constants, stability constants of their Zn(2+)/Mg(2+) complexes, and their species distribution. Analogues 3 and 4, in solution, adopted a predominant Southern ribose conformer (ca. 84%), gg conformation around C4'-C5' and C5'-O5' bonds, and glycosidic angle in the anti-region (213-270°). (1)H- and (31)P-NMR experiments indicated that Zn(2+)/Mg(2+) ions coordinated to P5' and P3' groups of 3 and 4 but not to N7 nitrogen atom. Analogues 3 and 4 formed ca. 100-fold more stable complexes with Zn(2+)vs. Mg(2+)-ions. Complexes of 3 and 4 with Mg(2+) at physiological pH were formed in minute amounts (11% and 8%, respectively) vs. Zn(2+) complexes (46% and 44%). Stability constants of Zn(2+)/Mg(2+) complexes of analogues 3 and 4 (log KML(M) = 4.65-4.75/2.63-2.79, respectively) were similar to those of the corresponding complexes of ADP and GDP (log KML(M) = 4.72-5.10/2.95-3.16, respectively). Based on the above findings, we hypothesized that the unexpectedly low log K values of Zn(2+)-d(pNp) as compared to Zn(2+)-NDP complexes, are possibly due to formation of outer-sphere coordination in the Zn(2+)-d(pNp) complex vs. inner-sphere in the NDP-Zn(2+) complex, in addition to loss of chelation to N7 nitrogen atom in Zn(2+)-d(pNp). Indeed, explicit solvent molecular dynamics simulations of 1 and 3 for 100 ns supported this hypothesis.
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Affiliation(s)
- Alon Haim Sayer
- Department of Chemistry and the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar Ilan University, Ramat-Gan 52900, Israel.
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Zhou P, Shi R, Yao JF, Sheng CF, Li H. Supramolecular self-assembly of nucleotide–metal coordination complexes: From simple molecules to nanomaterials. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2015.02.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sayer AH, Itzhakov Y, Stern N, Nadel Y, Fischer B. Characterization of complexes of nucleoside-5'-phosphorothioate analogues with zinc ions. Inorg Chem 2013; 52:10886-96. [PMID: 24050595 DOI: 10.1021/ic400878k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
On the basis of the high affinity of Zn(2+) to sulfur and imidazole, we targeted nucleotides such as GDP-β-S, ADP-β-S, and AP3(β-S)A, as potential biocompatible Zn(2+)-chelators. The thiophosphate moiety enhanced the stability of the Zn(2+)-nucleotide complex by about 0.7 log units. ATP-α,β-CH2-γ-S formed the most stable Zn(2+)-complex studied here, log K 6.50, being ~0.8 and ~1.1 log units more stable than ATP-γ-S-Zn(2+) and ATP-Zn(2+) complexes, and was the major species, 84%, under physiological pH. Guanine nucleotides Zn(2+) complexes were more stable by 0.3-0.4 log units than the corresponding adenine nucleotide complexes. Likewise, AP3(β-S)A-zinc complex was ~0.5 log units more stable than AP3A complex. (1)H- and (31)P NMR monitored Zn(2+) titration showed that Zn(2+) coordinates with the purine nucleotide N7-nitrogen atom, the terminal phosphate, and the adjacent phosphate. In conclusion, replacement of a terminal phosphate by a thiophosphate group resulted in decrease of the acidity of the phosphate moiety by approximately one log unit, and increase of stability of Zn(2+)-complexes of the latter analogues by up to 0.7 log units. A terminal phosphorothioate contributed more to the stability of nucleotide-Zn(2+) complexes than a bridging phosphorothioate.
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Affiliation(s)
- Alon Haim Sayer
- Department of Chemistry, Bar Ilan University , Ramat-Gan 52900, Israel
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Complex formation of cadmium with sugar residues, nucleobases, phosphates, nucleotides, and nucleic acids. Met Ions Life Sci 2013; 11:191-274. [PMID: 23430775 DOI: 10.1007/978-94-007-5179-8_8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cadmium(II), commonly classified as a relatively soft metal ion, prefers indeed aromatic-nitrogen sites (e.g., N7 of purines) over oxygen sites (like sugar-hydroxyl groups). However, matters are not that simple, though it is true that the affinity of Cd(2+) towards ribose-hydroxyl groups is very small; yet, a correct orientation brought about by a suitable primary binding site and a reduced solvent polarity, as it is expected to occur in a folded nucleic acid, may facilitate metal ion-hydroxyl group binding very effectively. Cd(2+) prefers the guanine(N7) over the adenine(N7), mainly because of the steric hindrance of the (C6)NH(2) group in the adenine residue. This Cd(2+)-(N7) interaction in a guanine moiety leads to a significant acidification of the (N1)H meaning that the deprotonation reaction occurs now in the physiological pH range. N3 of the cytosine residue, together with the neighboring (C2)O, is also a remarkable Cd(2+) binding site, though replacement of (C2)O by (C2)S enhances the affinity towards Cd(2+) dramatically, giving in addition rise to the deprotonation of the (C4)NH(2) group. The phosphodiester bridge is only a weak binding site but the affinity increases further from the mono- to the di- and the triphosphate. The same also holds for the corresponding nucleotides. Complex stability of the pyrimidine-nucleotides is solely determined by the coordination tendency of the phosphate group(s), whereas in the case of purine-nucleotides macrochelate formation takes place by the interaction of the phosphate-coordinated Cd(2+) with N7. The extents of the formation degrees of these chelates are summarized and the effect of a non-bridging sulfur atom in a thiophosphate group (versus a normal phosphate group) is considered. Mixed ligand complexes containing a nucleotide and a further mono- or bidentate ligand are covered and it is concluded that in these species N7 is released from the coordination sphere of Cd(2+). In the case that the other ligand contains an aromatic residue (e.g., 2,2'-bipyridine or the indole ring of tryptophanate) intramolecular stack formation takes place. With buffers like Tris or Bistris mixed ligand complexes are formed. Cd(2+) coordination to dinucleotides and to dinucleoside monophosphates provides some insights regarding the interaction between Cd(2+) and nucleic acids. Cd(2+) binding to oligonucleotides follows the principles of coordination to its units. The available crystal studies reveal that N7 of purines is the prominent binding site followed by phosphate oxygens and other heteroatoms in nucleic acids. Due to its high thiophilicity, Cd(2+) is regularly used in so-called thiorescue experiments, which lead to the identification of a direct involvement of divalent metal ions in ribozyme catalysis.
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Griffith DM, Szőcs B, Keogh T, Suponitsky KY, Farkas E, Buglyó P, Marmion CJ. Suberoylanilide hydroxamic acid, a potent histone deacetylase inhibitor; its X-ray crystal structure and solid state and solution studies of its Zn(II), Ni(II), Cu(II) and Fe(III) complexes. J Inorg Biochem 2011; 105:763-9. [DOI: 10.1016/j.jinorgbio.2011.03.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/09/2011] [Accepted: 03/10/2011] [Indexed: 01/24/2023]
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Csapó E, Buglyó P, Nagy NV, Santos MA, Corona A, Farkas E. Syntheses and characterization of Cu2+, Ni2+ and Zn2+ binding capability of histidinehydroxamic acid derivatives. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.08.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kiliç H. Electronic absorption study on acid-base equilibria for some pyrimidine derivatives containing semi- and thiosemicarbazone moiety. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 75:728-733. [PMID: 20018555 DOI: 10.1016/j.saa.2009.11.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 11/16/2009] [Accepted: 11/18/2009] [Indexed: 05/28/2023]
Abstract
The UV-vis spectra of recently synthesized 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-one, (I), and 5-benzoyl-1-(methylphenylmethyleneamino)-4-phenyl-1H-pyrimidine-2-thione, (II) were studied in aqueous methanol (5%, v/v methanol). The nature of the electronic transitions and the roles of carbonyl oxygen of I and thiocarbonyl sulfur of II on the behavior of UV-vis spectra were discussed. Acid-base equilibria of the compounds against varying pH and pK(a) values related equilibria were determined at an ionic strength of 0.10 M by using the Henderson-Haselbalch equation. The mean acidity constants for the protonated forms of the compounds were determined as pK(a1)=5.121, pK(a2)=7.929 and pK(a3)=11.130 for I and pK(a1)=4.684, pK(a2)=7.245 and pK(a3)=10.630 for II. The preferred dissociation mechanisms were discussed based on UV-vis data and a mechanism was proposed for each compound.
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Affiliation(s)
- H Kiliç
- Department of Physical Chemistry, Faculty of Sciences and Letters, Marmara University, Ziverbey 34722, Goztepe, Istanbul, Turkey.
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Sigel H, Operschall BP, Griesser R. Xanthosine 5'-monophosphate (XMP). Acid-base and metal ion-binding properties of a chameleon-like nucleotide. Chem Soc Rev 2009; 38:2465-94. [PMID: 19623361 DOI: 10.1039/b902181g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The four acidity constants of threefold protonated xanthosine 5'-monophosphate, H(3)(XMP)(+), reveal that in the physiological pH range around 7.5 (X - H x MP)(3-) strongly dominates and not XMP(2-) as commonly given in textbooks and often applied in research papers. Therefore, this nucleotide, which participates in many metabolic processes, should be addressed as xanthosinate 5'-monophosphate as is stated in this critical review. Micro acidity constant schemes allow quantification of intrinsic site basicities. In 9-methylxanthine nucleobase deprotonation occurs to more than 99% at (N3)H, whereas for xanthosine it is estimated that about 30% are (N1)H deprotonated and for (X - H x MP)(3-) it is suggested that (N1)H deprotonation is further favored, especially in macrochelates where the phosphate-coordinated M(2+) interacts with N7. The formation degree of these macrochelates in the (X - H x MP x M)(-) species of Co(2+), Ni(2+), Cu(2+), Zn(2+) or Cd(2+) amounts to 90% or more. In the monoprotonated (M x X - H x MP x H)(+/-) complexes, M(2+) is located at the N7/[(C6)O] unit as the primary binding site and it forms macrochelates with the P(O)(2)(OH)(-) group to about 65% for nearly all metal ions considered (i.e., including Ba(2+), Sr(2+), Ca(2+), Mg(2+)); this indicates outer-sphere binding to P(O)(2)(OH)(-). Finally, a new method quantifying the chelate effect is applied to the M(X - H x MP)(-) species, stabilities and structures of mixed-ligand complexes are considered, and the stability constants for several M(X - H x DP)(2-) and M(X - H x TP)(3-) complexes are estimated (112 references).
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Affiliation(s)
- Helmut Sigel
- Department of Chemistry, Inorganic Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
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Furler M, Knobloch B, Sigel RK. Influence of decreased solvent permittivity on the structure and magnesium(II)-binding properties of the catalytic domain 5 of a group II intron ribozyme. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2008.03.095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Operschall BP, Bianchi EM, Griesser R, Sigel H. Influence of decreasing solvent polarity (1,4-dioxane/water mixtures) on the stability and structure of complexes formed by copper(II), 2,2′-bipyridine or 1,10-phenanthroline and guanosine 5′-diphosphate: evaluation of isomeric equilibria. J COORD CHEM 2008. [DOI: 10.1080/00958970802474888] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Bert P. Operschall
- a Department of Chemistry, Inorganic Chemistry , University of Basel , Spitalstrasse 51, CH-4056 Basel, Switzerland
| | - Emanuela M. Bianchi
- a Department of Chemistry, Inorganic Chemistry , University of Basel , Spitalstrasse 51, CH-4056 Basel, Switzerland
| | - Rolf Griesser
- a Department of Chemistry, Inorganic Chemistry , University of Basel , Spitalstrasse 51, CH-4056 Basel, Switzerland
| | - Helmut Sigel
- a Department of Chemistry, Inorganic Chemistry , University of Basel , Spitalstrasse 51, CH-4056 Basel, Switzerland
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Mucha A, Knobloch B, Jezowska-Bojczuk M, Kozłowski H, Sigel RKO. Comparison of the acid-base properties of ribose and 2'-deoxyribose nucleotides. Chemistry 2008; 14:6663-71. [PMID: 18567033 DOI: 10.1002/chem.200800496] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The extent to which the replacement of a ribose unit by a 2'-deoxyribose unit influences the acid-base properties of nucleotides has not hitherto been determined in detail. In this study, by potentiometric pH titrations in aqueous solution, we have measured the acidity constants of the 5'-di- and 5'-triphosphates of 2'-deoxyguanosine [i.e., of H(2)(dGDP)(-) and H(2)(dGTP)(2-)] as well as of the 5'-mono-, 5'-di-, and 5'-triphosphates of 2'-deoxyadenosine [i.e., of H(2)(dAMP)(+/-), H(2)(dADP)(-), and H(2)(dATP)(2-)]. These 12 acidity constants (of the 56 that are listed) are compared with those of the corresponding ribose derivatives (published data) measured under the same experimental conditions. The results show that all protonation sites in the 2'-deoxynucleotides are more basic than those in their ribose counterparts. The influence of the 2'-OH group is dependent on the number of 5'-phosphate groups as well as on the nature of the purine nucleobase. The basicity of N7 in guanine nucleotides is most significantly enhanced (by about 0.2 pK units), while the effect on the phosphate groups and the N1H or N1H(+) sites is less pronounced but clearly present. In addition, (1)H NMR chemical shift change studies in dependence on pD in D(2)O have been carried out for the dAMP, dADP, and dATP systems, which confirmed the results from the potentiometric pH titrations and showed the nucleotides to be in their anti conformations. Overall, our results are not only of relevance for metal ion binding to nucleotides or nucleic acids, but also constitute an exact basis for the calculation, determination, and understanding of perturbed pK(a) values in DNAzymes and ribozymes, as needed for the delineation of acid-base mechanisms in catalysis.
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Affiliation(s)
- Ariel Mucha
- Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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Ali H, Nazzal M, Zaghloul AAA, Nazzal S. Comparison between lipolysis and compendial dissolution as alternative techniques for the in vitro characterization of α-tocopherol self-emulsified drug delivery systems (SEDDS). Int J Pharm 2008; 352:104-14. [DOI: 10.1016/j.ijpharm.2007.10.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 09/11/2007] [Accepted: 10/19/2007] [Indexed: 11/25/2022]
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Sigel H, Massoud SS, Song B, Griesser R, Knobloch B, Operschall BP. Acid-base and metal-ion-binding properties of xanthosine 5'-monophosphate (XMP) in aqueous solution: complex stabilities, isomeric equilibria, and extent of macrochelation. Chemistry 2007; 12:8106-22. [PMID: 16888737 DOI: 10.1002/chem.200600160] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The four acidity constants of threefold protonated xanthosine 5'-monophosphate, H3(XMP)+, reveal that at the physiological pH of 7.5 (XMP-H)(3-) strongly dominates (and not XMP(2-) as given in textbooks); this is in contrast to the related inosine (IMP(2-)) and guanosine 5'-monophosphate (GMP(2-)) and it means that XMP should better be named as xanthosinate 5'-monophosphate. In addition, evidence is provided for a tautomeric (XMP-HN1)(3-)/(XMP-HN3)(3-) equilibrium. The stability constants of the M(H;XMP)+ species were estimated and those of the M(XMP) and M(XMP-H)- complexes (M2+=Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+) measured potentiometrically in aqueous solution. The primary M2+ binding site in M(XMP) is (mostly) N7 of the monodeprotonated xanthine residue, the proton being at the phosphate group. The corresponding macrochelates involving P(O)2(OH)- (most likely outer-sphere) are formed to approximately 65% for nearly all M2+. In M(XMP-H)- the primary M2+ binding site is (mostly) the phosphate group; here the formation degree of the N7 macrochelates varies widely from close to zero for the alkaline earth ions, to approximately 50% for Mn2+, and approximately 90% or more for Co2+, Ni2+, Cu2+, Zn2+, and Cd2+. Because for (XMP-H)(3-) the micro stability constants quantifying the M2+ affinity of the xanthosinate and PO3(2-) residues are known, one may apply a recently developed quantification method for the chelate effect to the corresponding macrochelates; this chelate effect is close to zero for the alkaline earth ions and it amounts to about one log unit for Co2+, Ni2+, Cu2+. This method also allows calculation of the formation degrees of the monodentatally coordinated isomers; this information is of relevance for biological systems because it demonstrates how metal ions can switch from one site to another through macrochelate formation. These insights are meaningful for metal-ion-dependent reactions of XMP in metabolic pathways; previous mechanistic proposals based on XMP(2-) need revision.
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Affiliation(s)
- Helmut Sigel
- Department of Chemistry, Inorganic Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
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Sigel RKO, Pyle AM. Alternative Roles for Metal Ions in Enzyme Catalysis and the Implications for Ribozyme Chemistry. Chem Rev 2006; 107:97-113. [PMID: 17212472 DOI: 10.1021/cr0502605] [Citation(s) in RCA: 222] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Roland K O Sigel
- Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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Fernández-Botello A, Griesser R, Holý A, Moreno V, Sigel H. Acid-base and metal-ion-binding properties of 9-[2-(2-phosphonoethoxy)ethyl]adenine (PEEA), a relative of the antiviral nucleotide analogue 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA). An exercise on the quantification of isomeric complex equilibria in solution. Inorg Chem 2005; 44:5104-17. [PMID: 15998039 DOI: 10.1021/ic050341j] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The acidity constants of 3-fold protonated 9-[2-(2-phosphonoethoxy)ethyl]adenine, H3(PEEA)+, and of 2-fold protonated (2-phosphonoethoxy)ethane, H2(PEE), and the stability constants of the M(H;PEEA)+, M(PEEA), and M(PEE) complexes with M2+ = Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, or Cd2+ have been determined (potentiometric pH titrations; aqueous solution; 25 degrees C; I = 0.1 M, NaNO3). It is concluded that in the M(H;PEEA)+ species, the proton is at the phosphonate group and the metal ion at the adenine residue. The application of previously determined straight-line plots of log K(M(R-PO3))M versus pK(H(R-PO3))H for simple phosph(on)ate ligands, R-PO3(2-), where R represents a residue that does not affect metal-ion binding, proves that the M(PEEA) complexes of Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ as well as the M(PEE) complexes of Co2+, Cu2+, and Zn2+ have larger stabilities than is expected for a sole phosphonate coordination of M2+. For the M2+ complexes without an enhanced stability (e.g., Mg2+ or Mn2+), it is concluded that M2+ binds in a monodentate fashion to the phosphonate group of the two ligands. Combination of all of the results allows the following conclusions: (i) The increased stability of the Co(PEE), Cu(PEE), Zn(PEE), and Co(PEEA) complexes is due to the formation of six-membered chelates involving the ether-oxygen atom of the aliphatic residue (-CH2-O-CH2CH2-PO3(2-)) of the ligands with formation degrees of about 15-30%. (ii) Cd(PEEA) forms a macrochelate with N7 of the adenine residue (formation degree about 30%); Ni(PEEA) has similar properties. (iii) With Zn(PEEA), both mentioned types of chelates are observed, that is, Zn(PEEA)(cl/O) and Zn(PEEA)(cl/N7), with formation degrees of about 13 and 41%, respectively; the remaining 46% is due to the "open" isomer Zn(PEEA)(op) in which the metal ion binds only to the PO3(2-) group. (iv) Most remarkable is Cu(PEEA) because a fourth isomer, Cu(PEEA)(cl/O/N3), is formed that contains a six-membered ring involving the ether oxygen next to the phosphonate group and also a seven-membered ring involving N3 of the adenine residue with a very significant formation degree of about 50%. Hence, PEEA(2-) is a truly ambivalent ligand, its properties being strongly dependent on the kind of metal ion involved. Comparisons with M2+ complexes formed by the dianions of 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA) and related ligands reveal that five-membered chelates involving an ether-oxygen atom are considerably more stable than the corresponding six-membered ones. This observation offers an explanation of why PMEA is a nucleotide analogue with excellent antiviral properties and PEEA is not.
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Affiliation(s)
- Alfonso Fernández-Botello
- Department of Chemistry, Inorganic Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland
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Critical evaluation of stability constants for nucleotide complexes with protons and metal ions and the accompanying enthalpy changes. PURE APPL CHEM 1991. [DOI: 10.1351/pac199163071015] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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