On the Complexation of Ferric Ions by Reduced Nicotinamide Adenine Dinucleotide

Menachem Gutman; Michael Eisenbach

doi:10.1021/bi00736a020

On the Complexation of Ferric Ions by Reduced Nicotinamide Adenine Dinucleotide

Menachem Gutman^*, Michael Eisenbach

^*Corresponding author for this work

Biochemistry Molecular Biology

Tel Aviv University

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

In acid aqueous solutions, ferric ions and NADH were found to react rapidly to form a blue charge-transfer complex with a stoichiometry of Fe³⁺(NADH)₂. This complex is unstable and decomposes in a redox reaction with Fe²⁺ and NAD⁺ as products. The formation of the complex was studied under similar conditions by the stopped-flow technique and found to be a two-step reaction (see eq 1 and 2 of text). The rate constants of these two reactions were calculated from both kinetics and equilibrium studies. Within experimental error the results obtained by the two methods were the same (k₁ = (5.0 ± 0.2) × 10³ m^–1 sec^–1, k^–1 = 0.6 ± 0.1 sec^–1; k₂ = (1.30 ± 0.05) × 10₃ M^–1 sec^–1, k_–2 = 0.03 ± 0.01 sec^–1). The relatively small magnitude of k_–2 is the explanation for the complete conversion of Fe³⁺ into the Fe³⁺(NADH)₂ complex. The two complexes have similar absorption spectra with a maximum at 540 nm, except that the extinction coefficient of the Fe³⁺(NADH) is lower than that of Fe³⁺(NADH)₂. The properties of the Fe³⁺(NADH) complex are discussed.

Original language	English
Pages (from-to)	2314-2317
Number of pages	4
Journal	Biochemistry
Volume	12
Issue number	12
DOIs	https://doi.org/10.1021/bi00736a020
State	Published - 1 Jun 1973

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title = "On the Complexation of Ferric Ions by Reduced Nicotinamide Adenine Dinucleotide",

abstract = "In acid aqueous solutions, ferric ions and NADH were found to react rapidly to form a blue charge-transfer complex with a stoichiometry of Fe3+(NADH)2. This complex is unstable and decomposes in a redox reaction with Fe2+ and NAD+ as products. The formation of the complex was studied under similar conditions by the stopped-flow technique and found to be a two-step reaction (see eq 1 and 2 of text). The rate constants of these two reactions were calculated from both kinetics and equilibrium studies. Within experimental error the results obtained by the two methods were the same (k1 = (5.0 ± 0.2) × 103 m–1 sec–1, k–1 = 0.6 ± 0.1 sec–1; k2 = (1.30 ± 0.05) × 103 M–1 sec–1, k–2 = 0.03 ± 0.01 sec–1). The relatively small magnitude of k–2 is the explanation for the complete conversion of Fe3+ into the Fe3+(NADH)2 complex. The two complexes have similar absorption spectra with a maximum at 540 nm, except that the extinction coefficient of the Fe3+(NADH) is lower than that of Fe3+(NADH)2. The properties of the Fe3+(NADH) complex are discussed.",

author = "Menachem Gutman and Michael Eisenbach",

year = "1973",

month = jun,

day = "1",

doi = "10.1021/bi00736a020",

language = "אנגלית",

volume = "12",

pages = "2314--2317",

journal = "Biochemistry",

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T1 - On the Complexation of Ferric Ions by Reduced Nicotinamide Adenine Dinucleotide

AU - Gutman, Menachem

AU - Eisenbach, Michael

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N2 - In acid aqueous solutions, ferric ions and NADH were found to react rapidly to form a blue charge-transfer complex with a stoichiometry of Fe3+(NADH)2. This complex is unstable and decomposes in a redox reaction with Fe2+ and NAD+ as products. The formation of the complex was studied under similar conditions by the stopped-flow technique and found to be a two-step reaction (see eq 1 and 2 of text). The rate constants of these two reactions were calculated from both kinetics and equilibrium studies. Within experimental error the results obtained by the two methods were the same (k1 = (5.0 ± 0.2) × 103 m–1 sec–1, k–1 = 0.6 ± 0.1 sec–1; k2 = (1.30 ± 0.05) × 103 M–1 sec–1, k–2 = 0.03 ± 0.01 sec–1). The relatively small magnitude of k–2 is the explanation for the complete conversion of Fe3+ into the Fe3+(NADH)2 complex. The two complexes have similar absorption spectra with a maximum at 540 nm, except that the extinction coefficient of the Fe3+(NADH) is lower than that of Fe3+(NADH)2. The properties of the Fe3+(NADH) complex are discussed.

AB - In acid aqueous solutions, ferric ions and NADH were found to react rapidly to form a blue charge-transfer complex with a stoichiometry of Fe3+(NADH)2. This complex is unstable and decomposes in a redox reaction with Fe2+ and NAD+ as products. The formation of the complex was studied under similar conditions by the stopped-flow technique and found to be a two-step reaction (see eq 1 and 2 of text). The rate constants of these two reactions were calculated from both kinetics and equilibrium studies. Within experimental error the results obtained by the two methods were the same (k1 = (5.0 ± 0.2) × 103 m–1 sec–1, k–1 = 0.6 ± 0.1 sec–1; k2 = (1.30 ± 0.05) × 103 M–1 sec–1, k–2 = 0.03 ± 0.01 sec–1). The relatively small magnitude of k–2 is the explanation for the complete conversion of Fe3+ into the Fe3+(NADH)2 complex. The two complexes have similar absorption spectra with a maximum at 540 nm, except that the extinction coefficient of the Fe3+(NADH) is lower than that of Fe3+(NADH)2. The properties of the Fe3+(NADH) complex are discussed.

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On the Complexation of Ferric Ions by Reduced Nicotinamide Adenine Dinucleotide

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