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• W2049429077 abstract "The ortho, meta, and para isomers of manganese(III) 5,10,15,20-tetrakis(N-methylpyridyl)porphyrin, MnTM-2-PyP5+, MnTM-3-PyP5+, and MnTM-4-PyP5+, respectively, were analyzed in terms of their superoxide dismutase (SOD) activity in vitro and in vivo. The impact of their interaction with DNA and RNA on the SOD activity in vivo and in vitro has also been analyzed. Differences in their behavior are due to the combined steric and electrostatic factors. In vitro catalytic activities are closely related to their redox potentials. The half-wave potentials (E½) are +0.220 mV, +0.052 mV, and +0.060 Vversus normal hydrogen electrode, whereas the rates of dismutation (k cat) are 6.0 × 107, 4.1 × 106, and 3.8 × 106m−1 s−1 for theortho, meta, and para isomers, respectively.However, the in vitro activity is not a sufficient predictor of in vivo efficacy. The ortho and meta isomers, although of significantly different in vitro SOD activities, have fairly close in vivo SOD efficacy due to their similarly weak interactions with DNA. In contrast, due to a higher degree of interaction with DNA, thepara isomer inhibited growth of SOD-deficientEscherichia coli. The ortho, meta, and para isomers of manganese(III) 5,10,15,20-tetrakis(N-methylpyridyl)porphyrin, MnTM-2-PyP5+, MnTM-3-PyP5+, and MnTM-4-PyP5+, respectively, were analyzed in terms of their superoxide dismutase (SOD) activity in vitro and in vivo. The impact of their interaction with DNA and RNA on the SOD activity in vivo and in vitro has also been analyzed. Differences in their behavior are due to the combined steric and electrostatic factors. In vitro catalytic activities are closely related to their redox potentials. The half-wave potentials (E½) are +0.220 mV, +0.052 mV, and +0.060 Vversus normal hydrogen electrode, whereas the rates of dismutation (k cat) are 6.0 × 107, 4.1 × 106, and 3.8 × 106m−1 s−1 for theortho, meta, and para isomers, respectively. However, the in vitro activity is not a sufficient predictor of in vivo efficacy. The ortho and meta isomers, although of significantly different in vitro SOD activities, have fairly close in vivo SOD efficacy due to their similarly weak interactions with DNA. In contrast, due to a higher degree of interaction with DNA, thepara isomer inhibited growth of SOD-deficientEscherichia coli. superoxide dismutase N,N-dimethylformamide normal hydrogen electrode 4)-PyP4+, 5,10,15,20-tetrakis(N-methylpyridinium-2(3,4)-yl)porphyrin (ortho (2Sen A. Krishnan V.J. J. Chem. Soc. Faraday Trans. 1997; 93: 4281-4288Crossref Scopus (20) Google Scholar), meta (3Autret, M., Ou, Z., Boschi, A., Tagliatesta, P., Kadish, K. M.(1996) J. Chem. Soc. Dalton Trans. 2793–2797Google Scholar), and para(4Giraudeau A. Callot H.J. Jordan J. Ezhar I. Gross M. J. Am. Chem. Soc. 1979; 101: 3857-3862Crossref Scopus (233) Google Scholar) isomers) 4)-PyP5+, manganese(III) 5,10,15,20-tetrakis(N-methylpyridinium-2(3,4)-yl)porphyrin manganese(III) 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin manganese(III) 5,10,15,20-tetrakis(N-methylpyridyl)porphyrin tosylate. Due to their high stability and chemical versatility, manganese porphyrins are a promising group of compounds for development as SOD1 mimics. Introducing β-electron-withdrawing substituents and modifying mesosubstituents of water soluble porphyrins can have a major impact on the redox and electrostatic properties of manganese porphyrins (1Takeuchi T. Gray H.B. Goddard III, W.A. J. Am. Chem. Soc. 1994; 116: 9730-9732Crossref Scopus (113) Google Scholar, 2Sen A. Krishnan V.J. J. Chem. Soc. Faraday Trans. 1997; 93: 4281-4288Crossref Scopus (20) Google Scholar, 3Autret, M., Ou, Z., Boschi, A., Tagliatesta, P., Kadish, K. M.(1996) J. Chem. Soc. Dalton Trans. 2793–2797Google Scholar, 4Giraudeau A. Callot H.J. Jordan J. Ezhar I. Gross M. J. Am. Chem. Soc. 1979; 101: 3857-3862Crossref Scopus (233) Google Scholar, 5Tagliatesta P. Li J. Autret M. Van Caemelbecke E. Villard A. D'Souza F. Kadish K.M. J. Am. Chem. Soc. 1996; 35: 5570-5576Google Scholar, 6Binstead R.A. Crossley M.J. Hush N.S. Inorg. Chem. 1991; 30: 1259-1264Crossref Scopus (108) Google Scholar, 7Hariprasad, G., Dahal, S., and Maiya, B. G. (1996) J. Chem. Soc. Dalton Trans. 3429–3436Google Scholar). Such substitution allows the redox potential to approach the potential of SOD itself, E½ ∼ +0.26 V (8Barrette Jr., W.C. Sawyer D.T. Fee J.A. Asada K. Biochemistry. 1983; 22: 624-627Crossref PubMed Scopus (79) Google Scholar). This is approximately midway between the redox potentials of the two half-reactions of the dismutation process (9Koppenol W.H. Butler J. Adv. Free Radical Biol. Med. 1985; 1: 91-131Crossref Scopus (265) Google Scholar, 10Koppenol W.H. Bioelectrochem. Bioenerg. 1987; 18: 3-11Crossref Scopus (71) Google Scholar). While maintaining the redox potential at a value close to that of SOD, it is important to also ensure electrostatic facilitation. We have already shown that β-bromination (11Richards R.A. Hammons K. Joe M. Miskelly G.M. Inorg. Chem. 1996; 35: 1940-1944Crossref Scopus (52) Google Scholar, 12Tabata M. Nishimoto J. Ogata A. Kusano T. Nahar N. Bull. Chem. Soc. Jpn. 1996; 69: 673-677Crossref Scopus (37) Google Scholar) of the manganese(III) 5,10,15,20-tetrakis(N-methylpyridinium–4-yl)porphyrin (13Batinić-Haberle I. Liochev S.I. Spasojević I. Fridovich I. Arch. Biochem. Biophys. 1997; 343: 225-233Crossref PubMed Scopus (120) Google Scholar) and of manganese(III) 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin increases their SOD-like activities (13Batinić-Haberle I. Liochev S.I. Spasojević I. Fridovich I. Arch. Biochem. Biophys. 1997; 343: 225-233Crossref PubMed Scopus (120) Google Scholar). 2I. Batinić-Haberle and I. Fridovich, unpublished results. However, the large positive redox potential of the former, E½ = +0.480 mV versus NHE, (13Batinić-Haberle I. Liochev S.I. Spasojević I. Fridovich I. Arch. Biochem. Biophys. 1997; 343: 225-233Crossref PubMed Scopus (120) Google Scholar) stabilizes manganese in its 2+ state and diminishes stability, and the latter compound had only modest activity, probably due to lack of electrostatic facilitation (13Batinić-Haberle I. Liochev S.I. Spasojević I. Fridovich I. Arch. Biochem. Biophys. 1997; 343: 225-233Crossref PubMed Scopus (120) Google Scholar). It has been shown that ortho substitution on themeso phenyl ring exhibits an ortho effect that is as strong as if the same substituent were placed directly on themeso position (14Meot-Ner M. Adler A.D. J. Am. Chem. Soc. 1975; 97: 5107-5111Crossref Scopus (233) Google Scholar). Thus,meso-tetrakis(2-methylphenyl)porphyrin behaves similar to the meso tetramethylporphyrin (14Meot-Ner M. Adler A.D. J. Am. Chem. Soc. 1975; 97: 5107-5111Crossref Scopus (233) Google Scholar). The same was found for other porphyrins in which meso phenyl groups have differentortho substituents, as well as when meso groups are ortho pyridyls, such as 5,10,15,20-tetrakis-(N-methylpyridinium-2-yl) (H2TM-2-PyP4+) and its zinc complex, ZnTMP-2-PyP4+ (15Hambright P. Gore T. Burton M. Inorg. Chem. 1976; 15: 2314-2315Crossref Scopus (89) Google Scholar, 16Lee W.A. Gratzel M. Kalyanasundaram K. Chem. Phys. Lett. 1984; 107: 308-313Crossref Scopus (44) Google Scholar, 17Quimby D.J. Longo F.R. J. Am. Chem. Soc. 1975; 97: 5110-5117Crossref Scopus (331) Google Scholar, 18Vergeldt F.J. Koehorts R.B.M. Van Hoek A. Schaafsma T.J. J. Phys. Chem. 1995; 99: 4397-4405Crossref Scopus (168) Google Scholar, 19Valiotti A. Adeyemo A. Williams R.F.X. Ricks L. North J. Hambright P. J. Inorg. Nucl. Chem. 1981; 43: 2653-2658Crossref Scopus (28) Google Scholar). Such a profound impact on the properties of the ortho isomers, known as theortho effect, is due to the combined effect of inductive, resonance, and steric factors (20Kalyanasundaram K. Inorg. Chem. 1984; 23: 2453-2459Crossref Scopus (215) Google Scholar, 21Yu C.-H. Su Y.O. J. Electroanal. Chem. 1994; 368: 323-327Crossref Scopus (56) Google Scholar). For this reason, we explored the ortho isomer of manganese(III) 5,10,15,20-tetrakis(N-methylpyridyl)porphyrin (MnTMPyP5+) and expected more favorable electrostatic facilitation due to the positively charged pocket formed in both the αααα and αααβ atropoisomers (22Collman J.P. Gagne R.R. Reed C.A. Halbert T.R. Lang G. Robinson W.T. J. Am. Chem. Soc. 1975; 97: 1427-1439Crossref PubMed Scopus (931) Google Scholar, 23Collman J.P. Acc. Chem. Res. 1977; 10: 265-272Crossref Scopus (488) Google Scholar). Herein, we describe and compare the in vitro and in vivo SOD-like properties of the ortho, meta, and paraisomers of MnTMPyP5+. The relevant structures are shown in Fig. 1, together with force field molecular mechanics (MM2) model of the major αααβ atropoisomer. MnCl2·4H2O, and Baker-flex silica gel IB were purchased from J. T. Baker. 2-Propanol (99.5+ %),N,N-dimethylformamide (99.8+ % anhydrous), NH4PF6 (99.99%), sodiuml-ascorbate (99%), NaCl, tetrabutylammonium chloride, and protamine sulfate were from Sigma and Aldrich. RNA (type III from baker's yeast), DNA (type III from salmon sperm), xanthine, and cytochrome c (oxidized form) were purchased from Sigma. Methanol (anhydrous and absolute), ethanol (absolute), acetone, ethyl ether (anhydrous), KNO3, hydrochloric and sulfuric acids, phosphate salts, EDTA, glucose, inorganic salts, and KOH were from Mallinckrodt; acetonitrile was from Fisher; casamino acids were from Difco; and bovine Cu,Zn-SOD was from Diagnostic Data, Inc. Xanthine oxidase was prepared by R. Wiley and was supplied by K. V. Rajagopalan (24Waud W.R. Brady F.O. Wiley R.D. Rajagopalan K.V. Arch. Biochem. Biophys. 1975; 19: 695-701Crossref Scopus (180) Google Scholar). Catalase was from Boehringer Mannheim. Ultrapure argon was supplied from National Welders Supply Co. Molecular weight 3000 cut-off ultrafiltration (Centricon) concentrators were purchased from Amicon. The metal free porphyrins were obtained from Aldrich, Fluka, and Porphyrin Products (tosylate salts of the para isomer, H2TM-4-PyP4+) and from Mid-Century Chemicals (Posen, IL) (chloride salts of the ortho isomer, H2TM-2-PyP4+, and of the metaisomer, H2TM-3-PyP4+). The compounds were analyzed in terms of elemental analysis, UV-visible spectral characteristics of their di- and tetraprotonated forms (in the range of 0.5–50 μm), as well as in terms of thin-layer chromatography. Ortho isomer, H2TM-2-PyPCl4·4.5H2O (C44H47N8O4.5Cl4): calculated = C, 58.61; H, 5.25; N, 12.43; Cl, 15.73. Found = C, 58.62; H, 5.19; N, 12.31; Cl, 15.60. UV-visible for H2TM-2-PyP4+, λmax(log ε): 413.2(5.32), 510.4(4.13), 544.4(3.49), 581.4(3.72), 634.6(3.13). UV-visible for H4TM-2-PyP6+, λmax(log ε): 441.0(5.41), 578.4(4.17), 632.0(3.80). TLC (Baker-flex silica gel IB, KNO3sat:H2O:acetonitrile = 1:1:8),R f = 0.08. Meta isomer, H2TM-3-PyPCl4·2H2O (C44H42N8O2Cl4): calculated = C,61.69; H, 4.94; N, 13.08; Cl, 16.55. Found = C, 61.88; H, 5.01; N, 13.05; Cl, 16.33. UV-visible for H2TM-3-PyP4+, λmax(log ε): 416.6(5.50), 514.1(4.20), 550(shoulder), 581.2(3.77), 635.6(2.96). UV-visible for H4TM-3-PyP6+, λmax(log ε): 445.8(5.55), 593.7(4.03), 645.6(4.41). TLC (Baker-flex silica gel IB, KNO3sat:H2O:acetonitrile = 1:1:8),R f = 0.14. Para isomer, H2TM-4-PyPtos4(C72H66N8O12S4): calculated = C, 63.42; H, 4.88; N, 8.22; S, 9.40. Found = C, 62.11; H, 5.04; N, 8.09; S, 9.14. UV-visible for H2TM-2-PyP4+, λmax(log ε): 422.0(5.37), 518.4(4.19), 553.8(3.75), 584.0(3.79), 640.4(3.18). UV-visible for H4TM-4-PyP6+, λmax(log ε): 459.4(5.45), 603.8(4.09), 656.0(4.34). TLC (Baker-flex silica gel IB, KNO3sat: H2O: acetonitrile = 1: 1: 8), R f = 0.11. The manganese complexes were prepared by metallation of the porphyrin ligands in either water or in methanol at porphyrin:manganese ratios of 1:5, 1:13, and 1:100. In both solvents and at all metal to porphyrin ratios, the same compound, as evidenced by the Soret band, was obtained. Metallation in methanol was accomplished under refluxing conditions, whereas in water it was achieved at room temperature. When the pH of the water was raised to ∼12.3 (20Kalyanasundaram K. Inorg. Chem. 1984; 23: 2453-2459Crossref Scopus (215) Google Scholar,25Hambright P. Fleischer E. Inorg. Chem. 1955; 9: 1757-1761Crossref Scopus (223) Google Scholar), 3I. Batinić-Haberle, unpublished results; pK a (ortho) = 10.97, pK a (meta) = 13.1, pK a(para) = 12.9. ([H2TMPyP4+]/[HTMPyP3+][H+]). metallation was accomplished in ∼15 min. Routinely, a 1:20 ratio of porphyrin to metal in water at room temperature was applied. The reaction was monitored by UV-visible spectroscopy. Upon completion of metallation (pH brought to ∼7), the solution was filtered to remove manganese hydroxo species, and the PF6− salt of manganese complex was precipitated by the addition of a concentrated aqueous solution of NH4PF6 (11Richards R.A. Hammons K. Joe M. Miskelly G.M. Inorg. Chem. 1996; 35: 1940-1944Crossref Scopus (52) Google Scholar, 13Batinić-Haberle I. Liochev S.I. Spasojević I. Fridovich I. Arch. Biochem. Biophys. 1997; 343: 225-233Crossref PubMed Scopus (120) Google Scholar). The product was thoroughly washed with 2-propanol:diethyl ether = 1:1 and dried in vacuo at room temperature. The compound was then dissolved in acetone, the solution was filtered, and a concentrated acetone solution of tetrabutylammonium chloride was added, until the majority of the porphyrin had precipitated in the form of its chloride salt. The precipitate was washed thoroughly with acetone and dried in vacuo at room temperature. Usually the chloride salt was again dissolved in water and precipitated as PF6− salt. The latter was again dissolved in acetone and reisolated as chloride salt. This procedure ensured elimination of excess of metal. The chloride salts of metalloporphyrins were analyzed in terms of elemental analysis, UV-visible spectroscopy (in the range of 0.5–50 μm), and thin-layer chromatography. Ortho isomer, MnTM-2-PyPCl5·3.5H2O (MnC44H43N8O3.5Cl5): calculated = C, 54.37; H, 4.45; N, 11.52; Cl, 18.23. Found = C, 54.43; H, 4.56; N, 11.44; Cl, 18.18. TLC (Baker-flex silica gel IB, KNO3sat:H2O:acetonitrile = 1:1:8),R f = 0.048. Meta isomer, MnTM-3-PyPCl5·5H2O (MnC44H46N8O5Cl5): calculated = C, 52.89; H, 4.64; N, 11.21; Cl, 17.73. Found: C, 52.76; H, 4.55; N, 11.03; Cl, 17.64. TLC (Baker-flex silica gel IB, KNO3sat:H2O:acetonitrile = 1:1:8),R f = 0.055. Para isomer, MnTM-4-PyPCl5·5H2O (MnC44H46N8O5Cl5): calculated = C, 52.89; H, 4.64; N, 11.21; Cl, 17.73. Found: C, 53.18; H, 4.70; N, 11.12; Cl, 17.63. TLC (Baker-flex silica gel IB, KNO3sat:H2O:acetonitrile = 1:1:8),R f = 0.041. The UV-visible spectral characteristics are given in Table I, and the related spectra are given in Fig. 2.Table IOptical characteristics of the ortho, meta, and para isomers of MnTMPyPMnTMPyP5+Soret bandsQ bandsCharge transferλ, nm (log ɛ)Ortho362.8 (3.64), 453.4 (5.11)556.0 (4.03), 686.0 (2.93)781.0 (3.18)Meta372.8 (4.70), 395.2 (4.67)557.2 (4.11), 675.8 (3.13)765.6 (3.34)459.8 (5.14)Para376.4 (4.64), 399.8 (4.65)560.0 (4.07), 678.0 (3.08)769.5 (3.25)462.2 (5.11)The porphyrins were prepared and characterized as chloride salts, and spectral characteristics were determined in water. The estimated errors in ɛ are within ±2%. Open table in a new tab The porphyrins were prepared and characterized as chloride salts, and spectral characteristics were determined in water. The estimated errors in ɛ are within ±2%. We obtained ε(MnTM-4-PyP5+) = 130,000 cm−1m−1, whereas the literature value is 93,000 cm−1m−1 (26Harriman, A., and Porter, G. (1979) J. Chem. Soc. Faraday. Trans. II 1532–1542Google Scholar). Also, our molar absorptivity for MnTM-2-PyPCl5 is 129,000 cm−1m−1, whereas the literature value is 190,000 cm−1m−1 (27Hambright P. J. Inorg. Nucl. Chem. 1977; 39: 1102-1103Crossref Scopus (19) Google Scholar). One explanation for this discrepancy is the inadequate procedures used previously, usually aggressive ones that afford undesired substitution of the ring or even cause its reduction (27Hambright P. J. Inorg. Nucl. Chem. 1977; 39: 1102-1103Crossref Scopus (19) Google Scholar) and eventual degradation. The efficient yet nonaggressive metallation in water should be the most appropriate choice. Exposure of porphyrin to theN,N-dimethylformamide (DMF), especially when DMF is either a metallation medium or a solvent for modification of the porphyrin under refluxing conditions, during which it undergoes decomposition (28Kadish K.M. Araullo-McAdams C. Han B.C. Franzen M.M. J. Am. Chem. Soc. 1990; 112: 8364-8368Crossref Scopus (147) Google Scholar, 29Boschi T. Licoccia S. Tagliatesta P. Inorg. Chim. Acta. 1986; 119: 191-194Crossref Scopus (9) Google Scholar), should be avoided whenever possible. We have found that both metalloporphyrin (MnTMPyP5+) and its parent ligand (H2TMPyP4+) suffer significant changes when exposed to either anhydrous DMF or DMF/H2O (9:1) at ∼90 °C for prolonged periods. Thus, in 48 h, the molar absorptivity of a metal-free porphyrin falls to 50% of its initial value. The same happened when metalloporphyrin was left for 48 h in DMF/H2O (9:1) at ∼90 °C. Under anhydrous conditions, the metalloporphyrin is more resistant. The same changes were previously observed in the case of manganese(III) 5,10,15,20-tetrakis-(4-carboxyphenyl)porphyrin (MnTBAP+ 5). The modification of the porphyrin ring, hydrogen bonding interaction of the pyrrole nitrogen hydrogen with DMF (30Trofimov, B. A., Shatenshtein, A. I., Petrov, E. S., Terekhova, M. I., Golovanova, N. I., Mikhaleva, A. I., Korostova, S. E., and Vasil'ev, A. N., Khim. Geterotsikl. Soedin. (1980) 632–638Google Scholar), dimerization, and metal-centered reduction are among possible routes that can lead to the complete destruction of the porphyrin ring. 4I. Batinić-Haberle, unpublished results. The stability of manganese porphyrins was studied under strongly acidic and alkaline conditions and in the presence of up to 1000-fold excess EDTA. All three porphyrins were resistant to protonation as well as to ligand exchange. Even after ∼1 h in 36% hydrochloric acid, no demetallation was observed at ∼6 μm porphyrin concentration. A very slow demetallation was observed in 98% sulfuric acid in the case of meta compound, where ∼50% of demetallation occurred at 6 μm porphyrin in a 24-h period at room temperature. Under the same conditions, only negligible demetallation was observed in the case of para, whereas theortho isomer appeared to be the most resistant, showing no observable demetallation in 24 h. Their stability can be ascribed to the combination of steric hindrance and electronic effects (31Longo F.R. Brown E.M. Quimby D.J. Ann. N. Y. Acad. Sci. 1973; 206: 420-442Crossref PubMed Scopus (58) Google Scholar,32Davila, J., Harriman, A., Richoux, M.-C., and Milgrom, L. R. (1987) J. Chem. Soc. Chem. Commun. 525–527Google Scholar). The stability toward H2O2 was measured at 25 °C with 5 μm porphyrin, 5 mmH2O2 in 0.05 m phosphate buffer at pH 7.8. The half-times for the oxidative degradation of the porphyrin ring were 105, 28, and 30 s for the ortho, meta, and para isomers, respectively. This observation is consistent with their redox properties, i.e. resistance toward oxidation (anodic shift of both reduction and oxidation potentials) (1Takeuchi T. Gray H.B. Goddard III, W.A. J. Am. Chem. Soc. 1994; 116: 9730-9732Crossref Scopus (113) Google Scholar, 2Sen A. Krishnan V.J. J. Chem. Soc. Faraday Trans. 1997; 93: 4281-4288Crossref Scopus (20) Google Scholar, 3Autret, M., Ou, Z., Boschi, A., Tagliatesta, P., Kadish, K. M.(1996) J. Chem. Soc. Dalton Trans. 2793–2797Google Scholar, 4Giraudeau A. Callot H.J. Jordan J. Ezhar I. Gross M. J. Am. Chem. Soc. 1979; 101: 3857-3862Crossref Scopus (233) Google Scholar, 5Tagliatesta P. Li J. Autret M. Van Caemelbecke E. Villard A. D'Souza F. Kadish K.M. J. Am. Chem. Soc. 1996; 35: 5570-5576Google Scholar, 6Binstead R.A. Crossley M.J. Hush N.S. Inorg. Chem. 1991; 30: 1259-1264Crossref Scopus (108) Google Scholar, 7Hariprasad, G., Dahal, S., and Maiya, B. G. (1996) J. Chem. Soc. Dalton Trans. 3429–3436Google Scholar), due to the closer position and therefore greater inductive effect of the ortho positive charges on the porphyrin ring. Xanthine oxidase was the source of O⨪2, and ferricytochrome c was its indicating scavenger (33McCord J.M. Fridovich I. J. Biol. Chem. 1969; 244: 6049-6055Abstract Full Text PDF PubMed Google Scholar). Reduction of cytochrome c was followed at 550 nm. Assays were conducted in the presence and absence of 0.1 mm EDTA in 0.05 m phosphate buffer, pH 7.8, ± 15 μg/ml of catalase. Rate constants for the reaction of metalloporphyrins with O⨪2 were based upon the competition with 10 μmcytochrome c, k cyt c = 2.6 × 105m−1 s−1 (34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar). O⨪2 was produced at the rate of 1.2 μm/min. Possible interference through inhibition of the xanthine/xanthine oxidase reaction by test compounds was examined by following the rate of urate accumulation at 295 nm in the absence of cytochromec. All measurements were done at 25 °C. These interactions were followed by UV-visible spectroscopy, by cyclic voltammetry, through inhibition of their SOD-like activity, and by ultrafiltration. The interaction of metalloporphyrins with nucleic acids was performed both in the presence (27 mm) and absence of ascorbic acid in 0.05 mphosphate buffer, pH 7.8, at 6 μm porphyrin, 4.7 mm DNA and RNA. The RNA stock solutions, ranging between 18 and 76 mm, were prepared in water, whereas DNA stock solutions ranging between 18 and 38 mm were prepared in buffer due to the lower DNA solubility. The concentration of nucleic acids was calculated on the basis of mononucleotide. All the experiments with ascorbate were performed anaerobically in a specially designed cuvette (35Hodgson E.K. McCord J.M. Fridovich I. Anal. Biochem. 1973; 51: 470-473Crossref PubMed Scopus (19) Google Scholar) purged with argon. The retention of the porphyrins by a molecular weight 3000 cut-off filter ± the nucleic acids (11 and 22 mm) was determined filtering the 0.5 mmsolutions of porphyrin in 0.05 m phosphate buffer, pH 7.8, 0.1 m NaCl. The assay was performed at the porphyrin concentration that caused 50% inhibition of the cytochromec reduction (IC50). At the IC50porphyrin concentration, its SOD activity was titrated with nucleic acid in the concentration range of 0.4–21 μm, depending upon the isomer investigated. Measurements were performed using CH Instruments (computer supported) model 600 Voltammetric Analyzer. A three-electrode setup system in a small volume cell (0.5–3 ml, with a 3 mm-diameter button glassy carbon working electrode (Bioanalytical Systems) was used. Prior to each experiment, the electrode was cleaned with 0.3 μm alumina, sonicated in deionized water for 1 min, rinsed with stream of distilled water, wiped with a paper tissue, and allowed to air dry for 5 min. The reference electrode was a standard Ag/AgCl electrode (Bioanalytical Systems, 3 m NaCl gel filling solution), and the auxilliary electrode was a 0.5-mm platinum wire. Solutions containing 0.05m phosphate buffer, pH 7.8, 0.1 m NaCl and 0.5 mm metalloporphyrin were used. The effect of nucleic acids (0.05–45 mm) on the redox properties of the metalloporphyrins was studied. Ultrapure argon (less than 1 ppm oxygen), humidified, was purged through all the solutions for 30 min. Scan rates were 10–500 mV/s, typically 100 mV/s. Escherichia coli strains wild type AB1157 (control strain) and SOD-deficient JI132 (sodAsodB) were obtained from J. A. Imlay (36Imlay J.A. Linn S. J. Bacteriol. 1987; 169: 2967-2976Crossref PubMed Scopus (299) Google Scholar). Growth was followed in casamino acids medium and in minimal (five amino acids) medium (37Faulkner K.M. Liochev S.I. Fridovich I. J. Biol. Chem. 1994; 269: 23471-23476Abstract Full Text PDF PubMed Google Scholar). The cultures were diluted 1:200 from overnight cultures into minimal salts, 0.2% glucose, and 0.2% casamino acids and grown as described previously (37Faulkner K.M. Liochev S.I. Fridovich I. J. Biol. Chem. 1994; 269: 23471-23476Abstract Full Text PDF PubMed Google Scholar). Deionized water was used throughout. The porphyrins were added after inoculation in the range of 5–150 μm. Growth was followed turbidimetrically at 700 nm. Anaerobic conditions were achieved in a Coy chamber. The isomers of manganese(III)meso-tetrakis(N-methyl-pyridyl)porphyrin were prepared from their parent metal-free ligands and were characterized. The metal-free ligands were characterized as well, and their UV-visible data, given under “Materials and Methods,” agree well with literature data (15Hambright P. Gore T. Burton M. Inorg. Chem. 1976; 15: 2314-2315Crossref Scopus (89) Google Scholar). The metalloporphyrins resist strongly acidic (36% HCl) and basic conditions (1 m NaOH). Theortho isomer appeared thrice as resistant toward oxidative degradation with H2O2 than the paraone, which is consistent with the anodic shift of the redox potential due to the ortho effect (15Hambright P. Gore T. Burton M. Inorg. Chem. 1976; 15: 2314-2315Crossref Scopus (89) Google Scholar, 16Lee W.A. Gratzel M. Kalyanasundaram K. Chem. Phys. Lett. 1984; 107: 308-313Crossref Scopus (44) Google Scholar, 17Quimby D.J. Longo F.R. J. Am. Chem. Soc. 1975; 97: 5110-5117Crossref Scopus (331) Google Scholar, 18Vergeldt F.J. Koehorts R.B.M. Van Hoek A. Schaafsma T.J. J. Phys. Chem. 1995; 99: 4397-4405Crossref Scopus (168) Google Scholar, 19Valiotti A. Adeyemo A. Williams R.F.X. Ricks L. North J. Hambright P. J. Inorg. Nucl. Chem. 1981; 43: 2653-2658Crossref Scopus (28) Google Scholar, 20Kalyanasundaram K. Inorg. Chem. 1984; 23: 2453-2459Crossref Scopus (215) Google Scholar, 21Yu C.-H. Su Y.O. J. Electroanal. Chem. 1994; 368: 323-327Crossref Scopus (56) Google Scholar). The spectral characteristics of all isomers are given in Table I, and their UV-visible spectra in Fig. 2, A and B. Consistent with the sameortho effect, a blue shift of the Soret band was observed in the case of the ortho isomer. The molar absorptivities of the ortho and para isomers of manganese complexes were almost equal, as are the absorptivities of their diprotonated parent ligands as reported here and elsewhere (20Kalyanasundaram K. Inorg. Chem. 1984; 23: 2453-2459Crossref Scopus (215) Google Scholar). Inhibition of cytochrome creduction by the porphyrins, when plotted as (v o/v i) – 1 versusconcentration (38Sawada Y. Yamazaki I. Biochim. Biophys. Acta. 1973; 327: 257-265Crossref PubMed Scopus (92) Google Scholar) yielded a straight line as shown for theortho isomer in Fig. 3. The concentration that causes 50% of the inhibition of cytochromec reduction by O⨪2, IC50 (1 unit of activity) was found at (v o/v i) – 1 = 1. The activity of the compounds tested was also expressed as the percentage of the Cu,Zn-SOD activity, assumingk SOD = 2 × 109m−1 s−1 (34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar, 39McAdam M.E. Biochem. J. 1977; 161: 697-699Crossref PubMed Scopus (30) Google Scholar, 40Bielski B.H.J. Cabelli D.E. Arudi R.L. Ross A.B. J. Phys. Chem. Ref. Data. 1985; 14: 1041Crossref Scopus (1864) Google Scholar) and in terms of specific activity, i.e., units of the activity per milligram of the compound. No SOD activity was observed for all three isomers of metal-free porphyrins. None of these compounds interfered with the xanthine oxidase reaction. The addition of catalase at 15 μg/ml did not affect the SOD-like activity of the compounds. These data are given in Table II.Table IIResults of the cytochrome c assaysMnTMPyP5+IC50k cat% of SOD activitySpecific activitymmsunits/mgOrtho4.3 × 10−86.0 × 1073.008500Meta6.5 × 10−74.1 × 1060.20 560Para6.7 × 10−73.8 × 1060.18 550Cu,Zn-SOD1.3 × 10−92.0 × 1091005100Conditions: 0.05 m phosphate buffer, 0.1 mm EDTA, pH 7.8, 40 μm xanthine, ∼2 nm xanthine oxidase, ∼10 μm cytochromec. The rate of cytochrome c reduction by O⨪2, k cyt c = 2.6 × 105m−1 s−1 (34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar) is used for calculation of k cat. The estimated errors in IC50 are within ± 10%.Ref. 37Faulkner K.M. Liochev S.I. Fridovich I. J. Biol. Chem. 1994; 269: 23471-23476Abstract Full Text PDF PubMed Google Scholar.Refs. 33McCord J.M. Fridovich I. J. Biol. Chem. 1969; 244: 6049-6055Abstract Full Text PDF PubMed Google Scholar and 34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar. Open table in a new tab Conditions: 0.05 m phosphate buffer, 0.1 mm EDTA, pH 7.8, 40 μm xanthine, ∼2 nm xanthine oxidase, ∼10 μm cytochromec. The rate of cytochrome c reduction by O⨪2, k cyt c = 2.6 × 105m−1 s−1 (34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar) is used for calculation of k cat. The estimated errors in IC50 are within ± 10%. Ref. 37Faulkner K.M. Liochev S.I. Fridovich I. J. Biol. Chem. 1994; 269: 23471-23476Abstract Full Text PDF PubMed Google Scholar. Refs. 33McCord J.M. Fridovich I. J. Biol. Chem. 1969; 244: 6049-6055Abstract Full Text PDF PubMed Google Scholar and 34Butler J. Koppenol W.H. Margoliash E.J. J. Biol. Chem. 1982; 257: 10747-10750Abstract Full Text PDF PubMed Google Scholar. Crude cell extract of the SOD-deficient (sodAsodB) strain, added to the assay mixture, inhibited the SOD-like activity of these compounds. The presence of nucleic acids in the cell extract is responsible for that effect. Thus removal of nucleic acids by precipitation with protamine sulfate (41Warburg O. Christian W. Biochem. Z. 1939; 303: 40-68Google Scholar) eliminated this effect of crude extract. Neither the cell extract nor the protamine sulfate interfe" @default.
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• W2049429077 title "The Ortho Effect Makes Manganese(III)Meso-Tetrakis(N-Methylpyridinium-2-yl)Porphyrin a Powerful and Potentially Useful Superoxide Dismutase Mimic" @default.
• W2049429077 cites W1533259206 @default.
• W2049429077 cites W1591841427 @default.
• W2049429077 cites W1878196482 @default.
• W2049429077 cites W1940436875 @default.
• W2049429077 cites W1968727830 @default.
• W2049429077 cites W1968785665 @default.
• W2049429077 cites W1971252050 @default.
• W2049429077 cites W1976343257 @default.
• W2049429077 cites W1984052240 @default.
• W2049429077 cites W1989739972 @default.
• W2049429077 cites W1991215769 @default.
• W2049429077 cites W1994853861 @default.
• W2049429077 cites W2008321071 @default.
• W2049429077 cites W2008921949 @default.
• W2049429077 cites W2010350248 @default.
• W2049429077 cites W2012834867 @default.
• W2049429077 cites W2013035461 @default.
• W2049429077 cites W2013783614 @default.
• W2049429077 cites W2018816467 @default.
• W2049429077 cites W2021418205 @default.
• W2049429077 cites W2028260855 @default.
• W2049429077 cites W2032619989 @default.
• W2049429077 cites W2033082907 @default.
• W2049429077 cites W2035275179 @default.
• W2049429077 cites W2039349546 @default.
• W2049429077 cites W2046182336 @default.
• W2049429077 cites W2051388420 @default.
• W2049429077 cites W2051802937 @default.
• W2049429077 cites W2051810124 @default.
• W2049429077 cites W2053342328 @default.
• W2049429077 cites W2054463995 @default.
• W2049429077 cites W2058163851 @default.
• W2049429077 cites W2062505161 @default.
• W2049429077 cites W2064693243 @default.
• W2049429077 cites W2065175772 @default.
• W2049429077 cites W2066313697 @default.
• W2049429077 cites W2069299962 @default.
• W2049429077 cites W2073903901 @default.
• W2049429077 cites W2081833767 @default.
• W2049429077 cites W2082142902 @default.
• W2049429077 cites W2085280841 @default.
• W2049429077 cites W2086155660 @default.
• W2049429077 cites W2088259676 @default.
• W2049429077 cites W2091314579 @default.
• W2049429077 cites W2119657363 @default.
• W2049429077 cites W2190776221 @default.
• W2049429077 cites W2317773132 @default.
• W2049429077 cites W2318391338 @default.
• W2049429077 cites W2341795792 @default.
• W2049429077 cites W4249528615 @default.
• W2049429077 cites W4251276435 @default.
• W2049429077 cites W2075219428 @default.
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