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Monreal-Corona R, Biddlecombe J, Ippolito A, Mora-Diez N. Theoretical Study of the Iron Complexes with Lipoic and Dihydrolipoic Acids: Exploring Secondary Antioxidant Activity. Antioxidants (Basel) 2020; 9:E674. [PMID: 32731543 PMCID: PMC7465238 DOI: 10.3390/antiox9080674] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/24/2020] [Accepted: 07/25/2020] [Indexed: 12/19/2022] Open
Abstract
The thermodynamic stability of twenty-nine Fe(III) complexes with various deprotonated forms of lipoic (LA) and dihydrolipoic (DHLA) acids, with coordination numbers 4, 5 and 6, is studied at the M06(SMD)/6-31++G(d,p) level of theory in water under physiological pH conditions at 298.15 K. Even though the complexes with LA- are more stable than those with DHLA-, the most thermodynamically stable Fe(III) complexes involve DHLA2-. The twenty-four exergonic complexes are used to evaluate the secondary antioxidant activity of DHLA and LA relative to the Fe(III)/Fe(II) reduction by O2•- and ascorbate. Rate constants for the single-electron transfer (SET) reactions are calculated. The thermodynamic stability of the Fe(III) complexes does not fully correlate with the rate constant of their SET reactions, but more exergonic complexes usually exhibit smaller SET rate constants. Some Cu(II) complexes and their reduction to Cu(I) are also studied at the same level of theory for comparison. The Fe(III) complexes appear to be more stable than their Cu(II) counterparts. Relative to the Fe(III)/Fe(II) reduction with ascorbate, DHLA can fully inhibit the formation of •OH radicals, but not by reaction with O2•-. Relative to the Cu(II)/Cu(I) reduction with ascorbate, the effects of DHLA are moderate/high, and with O2•- they are minor. LA has minor to negligible inhibition effects in all the cases considered.
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Affiliation(s)
| | | | | | - Nelaine Mora-Diez
- Department of Chemistry, Thompson Rivers University, Kamloops, BC V2C 0C8, Canada; (R.M.-C.); (J.B.); (A.I.)
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P,N Codoped carbon dots as an efficient "off-on" fluorescent probe for lipoic acid detection and its cellular dual-color imaging. Anal Bioanal Chem 2019; 411:3603-3612. [PMID: 31129691 DOI: 10.1007/s00216-019-01842-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/21/2019] [Accepted: 04/10/2019] [Indexed: 12/14/2022]
Abstract
A facile single hydrothermal method was developed to synthetize P,N codoped carbon dots (P,N/CDs), which show strong and stable fluorescence, good water solubility, low toxicity and good biocompatibility. Hence, a novel and efficient "off-on" P,N/CDs fluorescent probe was developed for the highly sensitive detection of lipoic acid (LA) for the first time. The fluorescence of the P,N/CDs was quenched by Cu2+ forming a P,N/CDs-Cu2+ complex, which acted as the "off" process, but Cu2+ could be removed by LA, due to stronger chelating between LA and Cu2+, forming a more stable complex, which recovered the fluorescence of the P,N/CDs, in order to achieve the "on" process. Under optimal conditions, the concentration of LA and the increased fluorescence intensity of the P,N/CDs-Cu2+ complex displayed a good linear relationship within the range of 0.05-28 μM, with a detection limit (S/N = 3) of 0.02 μM. The established "off-on" fluorescent probe was successfully applied to the analysis of LA in urine samples. The average recoveries were in the range of 98.3-101.5%, with a relative standard deviations of less than 3.1%. In addition, the P,N/CDs were also successfully applied to cellular dual-color imaging of live T24 cells. The results show that the P,N/CDs have great application potential in clinical diagnosis, bioassay and bioimaging. Graphical abstract.
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Castañeda-Arriaga R, Alvarez-Idaboy JR, Mora-Diez N. Theoretical study of copper complexes with lipoic and dihydrolipoic acids. RSC Adv 2016. [DOI: 10.1039/c6ra23553k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A Cu(ii) complex with doubly-deprotonated dihydrolipoic acid has antioxidant capacity, since it is able to slow down by two orders the first step of the Haber–Weiss cycle reducing the potential damage caused by ˙OH radical formation.
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Affiliation(s)
- Romina Castañeda-Arriaga
- Facultad de Química
- Departamento de Física y Química Teórica
- Universidad Nacional Autónoma de México
- Mexico
- Department of Chemistry
| | - J. Raul Alvarez-Idaboy
- Facultad de Química
- Departamento de Física y Química Teórica
- Universidad Nacional Autónoma de México
- Mexico
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Yamamoto H, Watanabe T, Mizuno H, Endo K, Fukushige J, Hosokawa T, Kazusaka A, Fujita S. The antioxidant effect of DL-alpha-lipoic acid on copper-induced acute hepatitis in Long-Evans Cinnamon (LEC) rats. Free Radic Res 2001; 34:69-80. [PMID: 11234997 DOI: 10.1080/10715760100300071] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The Long-Evans Cinnamon (LEC) rats, due to a genetic defect, accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease and spontaneously develop acute hepatitis with severe jaundice. In this study we examined the protective effect of DL-alpha-Lipoic acid (LA) against acute hepatitis in LEC rats. LA was administered to LEC rats by gavage in doses of 10, 30 and 100 mg/kg five times per week, starting at 8-weeks-old and continuing till 12-weeks-old. Although LA had little effect against the increases in serum transaminase activities, it suppressed the loss of body weight and prevented severe jaundice in a dose-dependent manner. Antioxidant system analyses in liver showed that LA treatment significantly suppressed the inactivations of catalase and glutathione peroxidase, and the induction of heme oxygenase-1, an enzyme which is inducible under oxidative stress. Furthermore, LA showed dose-dependent suppressive effect against increase in nonheme iron contents of both cytosolic and crude mitochondrial fractions in a dose-dependent manner. Although at the highest dose, LA slightly suppressed the accumulation of Cu in crude mitochondrial fraction, it had no effect on the accumulation of Cu in cytosolic fraction. While LA completely suppressed the increase in lipid peroxidation (LPO) in the microsomal fraction at the highest dose, the suppressive effect against LPO in crude mitochondrial fractions was slight. From these results, it is concluded that LA has antioxidant effects at the molecular level against the development of Cu-induced hepatitis in LEC rats. Moreover, mitochondrial oxidative damage might be involved in the development of acute hepatitis in LEC rats.
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Affiliation(s)
- H Yamamoto
- Medicinal Safety Research Laboratories, Sankyo Co., Ltd., Tokyo, Japan
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Crévisy C, Herbage B, Marrel ML, Toupet L, Grée R. A New Iron-Mediated Strategy for the Synthesis of α-Lipoic Acid and Analogues. European J Org Chem 1998. [DOI: 10.1002/(sici)1099-0690(199809)1998:9<1949::aid-ejoc1949>3.0.co;2-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Biewenga GP, Haenen GR, Bast A. The pharmacology of the antioxidant lipoic acid. GENERAL PHARMACOLOGY 1997; 29:315-31. [PMID: 9378235 DOI: 10.1016/s0306-3623(96)00474-0] [Citation(s) in RCA: 534] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. Lipoic acid is an example of an existing drug whose therapeutic effect has been related to its antioxidant activity. 2. Antioxidant activity is a relative concept: it depends on the kind of oxidative stress and the kind of oxidizable substrate (e.g., DNA, lipid, protein). 3. In vitro, the final antioxidant activity of lipoic acid is determined by its concentration and by its antioxidant properties. Four antioxidant properties of lipoic acid have been studied: its metal chelating capacity, its ability to scavenge reactive oxygen species (ROS), its ability to regenerate endogenous antioxidants and its ability to repair oxidative damage. 4. Dihydrolipoic acid (DHLA), formed by reduction of lipoic acid, has more antioxidant properties than does lipoic acid. Both DHLA and lipoic acid have metal-chelating capacity and scavenge ROS, whereas only DHLA is able to regenerate endogenous antioxidants and to repair oxidative damage. 5. As a metal chelator, lipoic acid was shown to provide antioxidant activity by chelating Fe2+ and Cu2+; DHLA can do so by chelating Cd2+. 6. As scavengers of ROS, lipoic acid and DHLA display antioxidant activity in most experiments, whereas, in particular cases, pro-oxidant activity has been observed. However, lipoic acid can act as an antioxidant against the pro-oxidant activity produced by DHLA. 7. DHLA has the capacity to regenerate the endogenous antioxidants vitamin E, vitamin C and glutathione. 8. DHLA can provide peptide methionine sulfoxide reductase with reducing equivalents. This enhances the repair of oxidatively damaged proteins such as alpha-1 antiprotease. 9. Through the lipoamide dehydrogenase-dependent reduction of lipoic acid, the cell can draw on its NADH pool for antioxidant activity additionally to its NADPH pool, which is usually consumed during oxidative stress. 10. Within drug-related antioxidant pharmacology, lipoic acid is a model compound that enhances understanding of the mode of action of antioxidants in drug therapy.
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Affiliation(s)
- G P Biewenga
- Leiden/Amsterdam Center for Drug Research, Vrije Universiteit, Department of Pharmacochemistry, The Netherlands
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Biewenga GP, Haenen GRMM, Groen BH, Biewenga JE, van Grondelle R, Bast A. Combined non-enzymatic and enzymatic reduction favors bioactivation of racemic lipoic acid: an advantage of a racemic drug? Chirality 1997. [DOI: 10.1002/(sici)1520-636x(1997)9:4<362::aid-chir8>3.0.co;2-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Schepkin V, Kawabata T, Tritschler HJ, Packer L. 2D NMR of the metabolic antioxidant dihydrolipoic acid and its derivatives. Free Radic Res 1996; 25:195-205. [PMID: 8889486 DOI: 10.3109/10715769609149045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Dihydroplipoate and lipoate are physiological thiols which in addition to their coenzyme functions exhibit antioxidant activity. For NMR investigations of their protective mechanism in biological and model systems it is very important to know the full assignment of proton and carbon spectra of these molecules in water (D2O). An unambiguous assignment of proton and carbon NMR spectra has been made for dihydrolipoate and its short chain derivatives bisnor- and tetranor-lipoic acid in D2O and CDCl3 solutions using 2D NMR methods. Oxidation of dihydrolipoic acid produces substantial electron density deshielding of the carbons nearest to the SH groups with the largest shift found at the inner SH group (17.79 ppm in D2O, 16.93 in CDCl3) and almost no changes in the tail portion of the molecule. However, bisnor-dihydrolipoic acid and especially tetranor-dihydrolipoic acid have more carbon deshielding near the outer SH group of the molecule which correlates with their known diminished ion chelating activity. Moreover, the proton triplet at position 2 of lipoic acid has strong pH dependence (pK = 4.58) due to the close proximity to the carboxylic group and this feature may be used for monitoring pH.
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Affiliation(s)
- V Schepkin
- Department of Molecular & Cell Biology, University of California, Berkely 94720-3200, USA
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Sigel H. Quantification of successive intramolecular equilibria in binary metal ion complexes of N,N-bis(2-hydroxyethyl)glycinate (Bicinate). A case study. Coord Chem Rev 1993. [DOI: 10.1016/0010-8545(93)80046-8] [Citation(s) in RCA: 21] [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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Corfù NA, Song B, Liang-nian J. Metal ion/buffer interactions. Stability of binary and ternary metal ion complexes containing the anion of N,N-bis(2-hydroxyethyl)-glycine (bicine) and adenosine 5′-triphosphate (ATP). Inorganica Chim Acta 1992. [DOI: 10.1016/s0020-1693(00)80766-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ternary complexes in solution. Part 51. Intramolecular hydrophobic and stacking interactions in mixed ligand complexes containing Cu(II), 2,2′-bipyridyl or 1,10-phenanthroline, and a simple phosphate monoester, D-ribose 5′-monophosphate or a nucleoside 5′-monophosphate (CMP, UMP, TMP, TuMP) with a non-coordinating base residue. Inorganica Chim Acta 1989. [DOI: 10.1016/s0020-1693(00)80574-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Sigel H. Hydrophobic interactions in biological systems: some background information based on ligand-ligand interactions in metal ion complexes. PURE APPL CHEM 1989. [DOI: 10.1351/pac198961050923] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Martin RB, Sigel H. Quantification of Intramolecular Ligand Equilibria in Metal-Ion Complexes. COMMENT INORG CHEM 1988. [DOI: 10.1080/02603598808072294] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Belen'Kii L. The Literature of Heterocyclic Chemistry, Part III. ADVANCES IN HETEROCYCLIC CHEMISTRY VOLUME 44 1988. [DOI: 10.1016/s0065-2725(08)60264-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Sigel H. Isomeric equilibria in complexes of adenosine 5'-triphosphate with divalent metal ions. Solution structures of M(ATP)2- complexes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 165:65-72. [PMID: 3569298 DOI: 10.1111/j.1432-1033.1987.tb11194.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Solution structures of M(ATP)2- complexes are reviewed. First the self-stacking properties of ATP4- and M(ATP)2- are shortly described. It is emphasized that for an evaluation of solution structures of M(ATP)2- complexes only results from diluted solutions (below 1 mM) should be used. Next, a comprehensive set of stability data obtained under such conditions from potentiometric pH titrations is summarized for the complexes of Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+ with ATP, and for comparison also with pyrimidine nucleoside 5'-triphosphates (YTPs), i.e. CTP, UTP and TTP. The stabilities for the M(ATP)2- complexes are mostly larger than those for the corresponding M(YTP)2- species; this increased stability results from the metal ion back-binding to the base residue in M(ATP)2-, i.e. macrochelates are formed. Detailed analysis of the stability data allows calculation of the percentage of the closed form for the several M(ATP)2- complexes: back-binding is most pronounced in Cu(ATP)2- (67 +/- 2%), remarkable in Zn(ATP)2- (28 +/- 7%), and not observable for Ca(ATP)2- (2 +/- 6%). Comparison of these results with those from 1H-NMR and ultraviolet spectrophotometric studies allows the conclusion that two types of base back-bound macrochelates are formed: one with a direct, i.e. innersphere, M2+/N-7 coordination, and one with a water molecule between the metal ion and N-7, i.e. an outersphere interaction occurs [e.g. to about 10% in Mg(ATP)2-] through hydrogen bonding of a coordinated water to N-7. The formation degree of both forms of these closed isomers is quantified. The biological implications of these results are indicated and the versatility of ATP as a ligand is discussed by summarizing pertinent examples.
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Sigel H, Martin RB, Tribolet R, Häring UK, Malini-Balakrishnan R. An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate-metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 152:187-93. [PMID: 3930243 DOI: 10.1111/j.1432-1033.1985.tb09180.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The stability constants of the 1:1 complexes between Cu2+ and Zn2+ with formate, acetate and several phenylalkanecarboxylates, i.e. C6H5-(CH2)n-COO- with n = 0 to 5, are summarized for water, 50% aqueous ethanol and 50% aqueous dioxane (I = 0.1 M; 25 degrees C): Complex stability depends upon carboxylate group basicity. The influence of varying amounts of ethanol or dioxane (up to 90%) on the stability of the Cu2+ and Zn2+ (M2+) complexes with formate and acetate (CA) was measured by potentiometric pH titrations. The values for pKHH(CA) and log KMM(CA) increase, as expected, with increasing amounts of the organic solvents, i.e. with decreasing solvent polarity. The changes in the equilibrium constants are also evaluated with regard to the mole fractions of the organic solvents and the corresponding dielectric constants. These results may be used to estimate for low dielectric cavities in proteins the equivalent solution dielectric constant on the basis of enhanced carboxylate basicity or metal ion binding capability (method 1). Furthermore, the measured stability constants are used for comparisons of the coordination tendency of carboxylate ligands towards zinc(II)-metalloenzymes (method 2); in this way the equivalent solution dielectric constants in the active-site cavities of bovine carbonic anhydrase and carboxypeptidase A are estimated: the values are of the order of 35 and 70, respectively. This method seems to be generally applicable to metalloproteins.
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Sigel H, Tribolet R, Scheller KH. Solvent effects on intramolecular hydrophobic ligandligand interactions in binary and ternary complexes. Inorganica Chim Acta 1985. [DOI: 10.1016/s0020-1693(00)88303-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sigel H, Scheller KH. On the metal-ion coordinating properties of the 5'-monophosphates of 1, N6-ethenoadenosine (epsilon-AMP), adenosine and uridine. Comparison of the macrochelate formation in the complexes of epsilon-AMP, AMP, ADP and ATP. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 138:291-9. [PMID: 6321171 DOI: 10.1111/j.1432-1033.1984.tb07914.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The concentration dependence of the chemical shifts of the protons H-2, H-8, H-10, H-11, and H-1' of 1,N6-ethenoadenosine 5'-monophosphate (epsilon-AMP2-) has been measured. The results are consistent with the isodesmic model of indefinite noncooperative stacking; the association constant, K = 2.5 +/- 0.3 M-1, is within experimental error identical to the value determined earlier for AMP2-,K = 2.1 +/- 0.4 M-1. The conditions for the potentiometric pH titrations, used to determine the acidity constants of H2(epsilon-AMP), H2(AMP), and H(UMP)- and the stability constants of the metal ion (M2+) complexes of the corresponding nucleoside 5'-monophosphates (NMP), were chosen so that the ligands were present in the monomeric form. The stabilities of Mg(epsilon-AMP) and Mg(AMP) are similar; however, the stabilities of the Mn2+, Cu2+ and Zn2+ complexes of epsilon-AMP2- are much larger (in the case of Cu2+ by a factor of 700) than those of AMP2-. This is due to the much larger metal ion affinity of the epsilon-adenosine moiety compared to that of the parent adenosine residue. As the uridine moiety does not participate in complex formation, the stability constants of M(UMP) have been used to evaluate the extent of macrochelation (i.e. the simultaneous coordination of M2+ to the base moiety and the phosphate group) in the epsilon-AMP and AMP complexes: the concentration of the macrochelated isomer is considerably larger for M(epsilon-AMP) than for M(AMP). A comparison with previous results for the complexes with ADP3- and ATP4- indicates the order, M(AMP)cl less than M(ADP)-cl greater than M(ATP)2-cl for the tendency to form macrochelates (cl). Due to the relatively high affinity of the epsilon-adenosine moiety towards Mn2+, Cu2+ and Zn2+, the phosphate-monoprotonated complexes M(H . epsilon-AMP)+ also become important; the corresponding complexes play only a minor role in the M2+/AMP systems. Intramolecular aromatic-ring stacking occurs in the ternary Cu(2,2'-bipyridyl)(NMP) complexes: about 80% of Cu(Bpy)(AMP) and Cu(Bpy)(epsilon-AMP) exist as the stacked isomer in aqueous solution; for the former system it has been shown in a previous X-ray study that the intramolecular ligand-ligand interaction occurs also in the solid state [Aoki, K. (1978) J. Am. Chem. Soc. 100, 7106]. Overall, the results emphasize that great care should be exercised in drawing conclusions based on studies of metal-ion-containing enzymic systems in which the natural adenine nucleotide cofactors have been replaced by the corresponding 1,N6-etheno derivatives.
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