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Titolo:
Pulse radiolytic studies of metallotexaphyrins in the presence of oxygen: Relevance of the equilibrium with superoxide anion to the mechanism of action of the radiation sensitizer motexafin gadolinium (Gd-Tex(2+), Xcytrin)
Autore:
Sessler, JL; Tvermoes, NA; Guldi, DM; Hug, GL; Mody, TD; Magda, D;
Indirizzi:
Univ Texas, Dept Chem & Biochem, Austin, TX 78712 USA Univ Texas Austin TX USA 78712 Dept Chem & Biochem, Austin, TX 78712 USA Univ Notre Dame, Radiat Lab, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 iat Lab, Notre Dame, IN 46556 USA Pharmacycl Inc, Sunnyvale, CA 94086 USA Pharmacycl Inc Sunnyvale CA USA 94086 macycl Inc, Sunnyvale, CA 94086 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 7, volume: 105, anno: 2001,
pagine: 1452 - 1457
SICI:
1520-6106(20010222)105:7<1452:PRSOMI>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTRON-TRANSFER REACTIONS; RATE CONSTANTS; REDUCTION POTENTIALS; AQUEOUS-SOLUTION; FREE-RADICALS; APOPTOSIS; MITOCHONDRIA; TEXAPHYRIN; ASCORBATE; DEATH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Sessler, JL Univ Texas, Dept Chem & Biochem, Austin, TX 78712 USA Univ Texas Austin TX USA 78712 Biochem, Austin, TX 78712 USA
Citazione:
J.L. Sessler et al., "Pulse radiolytic studies of metallotexaphyrins in the presence of oxygen: Relevance of the equilibrium with superoxide anion to the mechanism of action of the radiation sensitizer motexafin gadolinium (Gd-Tex(2+), Xcytrin)", J PHYS CH B, 105(7), 2001, pp. 1452-1457

Abstract

Pulse radiolytic studies of aqueous solutions of four representative metallotexaphyrin complexes M-Tex(2+) (M = Gd(III), Lu(III), Dy(III), and Y(III)), carried out in the presence of either dioxygen, or trimethyl-p-benzoquinone (TMQ). It was found that all four of these M-Tex(2+) species set up an equilibrium with superoxide and the singly reduced TMQ (TMQ(.-)) on the pulse radiolytic time scale. Rate constants for the forward (k(1)) and back (k(-t)) reactions of Gd-Tex(2+) with superoxide anions, at pH 8.5, were determined to be (9.8 +/- 1.5) x 10(6) M-t s(-1) and (3.4 +/- 0.5) x 10(6) M-1 analogous rate constants were found to be (1.5 +/- 0.2) x 10(7) M-1 s(-1) and (3.7 +/- 0.6) x 10(6) M-1 s(-1) respectively. Equilibrium constants (K-kin,), calculated from these kinetic parameters, were found to be 2.9 and 4.1for Gd-Tex(2+) reacting with O-2(.-) (to produce Gd-Tex(.+) and O-2) and TMQ(.-) (to produce Gd-Tex(.+) and TMQ), respectively. Equilibrium constantsfor the M-Tex(2+) species reacting with O-2(.-) and TMQ(.-) were also determined from analysis of the absorption following establishment of the equilibrium. The resulting values for Gd-Tex(2+) were found to be 6.8 and 10.7, respectively. From these equilibrium constants, the redox potential for theM-Tex(2+)/M-Tex(.+) couples at pH 8.5 were estimated and found to be ca. -110 mV vs s(-1) and (3.4 +/- 0.5) x 10(6) M-1 NHE in the case of Gd-Tex'S s(-1), respectively. From these equilibrium constants, the redox potential for the M-Tex(2+)/M-Tex(.+) couples at pH 8.5 were estimated and found to baca. -110 mV vs NHE in the case of Gd-Tex(2+).

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Documento generato il 06/04/20 alle ore 08:43:06