Pyridoxal phosphate modified cytochromes c. Identification and electron transfer properties

Атанасов, Б.; Mitovska, Maria I.; Mancheva, Ivanka; Kossekova, Ganka P.; Tchorbanov, B.; Christova, Petia; Dancheva, Kirana I.

doi:10.1016/0005-2728(84)90173-7

Cited by 11 publications

(6 citation statements)

References 28 publications

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“…Data for k0 in Table 1 are in line with our previous results for restoration of respiration in cytochrome cdepleted mitochondria by native and pyridoxal 5'phosphate-modified cytochromes c [24]. The activity of any of the three cytochrome c oxidase preparations towards the different forms of cytochrome c decreases in the order native cytochrome c > [P-Pxy-Lys-79]cytochrome c > [P-Pxy-Lys-86]cytochrome c > [P-Pxy-Lys-79,P-Pxy-Lys-86]cytochrome c (Figs.…”

Section: Discussionsupporting

confidence: 89%

“…The activity of any of the three cytochrome c oxidase preparations towards the different forms of cytochrome c decreases in the order native cytochrome c > [P-Pxy-Lys-79]cytochrome c > [P-Pxy-Lys-86]cytochrome c > [P-Pxy-Lys-79,P-Pxy-Lys-86]cytochrome c (Figs. 1-3 and Table 1), though the derivatives have the same redox potential and overall conformation as native cytochrome c [24]. The higher affinity of the oxidase for [P-Pxy-Lys-79]cytochrome c than for [P-Pxy-Lys-86]cytochrome c (Figs I and 2) can be explained by the different positions of Lys-79 and Lys-86 relative to the dipole axis of the charged multipole of cytochrome c [3].…”

Section: Discussionmentioning

confidence: 99%

“…Pyridoxal 5'-phosphate-modified derivatives of cytochrome c were prepared as described in ref. [24]. Native and modified cytochromes c were reduced with dithionite.…”

Section: Methodsmentioning

confidence: 99%

“…The present paper describes studies on the complex cytochrome c oxidase reaction predominantly at lower ionic strengths. Three different cytochrome c oxidase preparations (purified phospholipid-depleted enzyme [21], enzyme reconstituted into phospholipid vesicles [22] and subunit-ITI-depeted enzyme [23]) were chosen to analyse the interaction with native and pyridoxal 5'phosphate-modified cytochromes c [24], thus providing different model systems. The derivatives of cytochrome c modified by negatively charged pyridoxal 5'-phosphate, namely [P-Pxy-Lys-79]cytochrome c, [P-Pxy-Lys-86]cytochrome c and [P-Pxy-Lys-79,P-Pxy-Lys-86]cytochrome c, have the same overall conformation and redox potentials as native cytochrome c, but their abilities to restore respiration in cytochrome c-depleted mitochondria are different: native cytochrome c > [P-Pxy-79]cytochrome c > [P-Pxy-Lys-86]cytochrome c > [P-Pxy-Lys-79,P-Pxy-Lys-86]cytochrome c [24].…”

Section: Introductionmentioning

confidence: 99%

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Ionic-strength-dependence of the oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by cytochrome c oxidase

Kossekova

Атанасов

Bolli

et al. 1989

Biochemical Journal

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The ionic-strength-dependences of the rate constants (log k plotted versus square root of 1) for oxidation of native and pyridoxal 5'-phosphate-modified cytochromes c by three different preparations of cytochrome c oxidase have complex non-linear character, which may be explained on the basis of present knowledge of the structure of the oxidase and the monomer-dimer equilibrium of the enzyme. The wave-type curve (with a minimum and a maximum) for oxidation of native cytochrome c by purified cytochrome c oxidase depleted of phospholipids may reflect consecutively inhibition of oxidase monomers (initial descending part), competition between this inhibition and dimer formation, resulting in increased activity (second part with positive slope), and finally inhibition of oxidase dimers (last descending part of the curve). The dependence of oxidation of native cytochrome c by cytochrome c oxidase reconstituted into phospholipid vesicles is a curve with a maximum, without the initial descending part described above. This may reflect the lack of pure monomers in the vesicles, where equilibrium is shifted to dimers even at low ionic strength. Subunit-III-depleted cytochrome c oxidase does not exhibit the maximum seen with the other two enzyme preparations. This may mean that removal of subunit III hinders dimer formation. The charge interactions of each of the cytochromes c (native or modified) with the three cytochrome c oxidase preparations are similar, as judged by the similar slopes of the linear dependences at I values above the optimal one. This shows that subunit III and the phospholipid membrane do not seem to be involved in the specific charge interaction of cytochrome c oxidase with cytochrome c.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

“…Pyridoxal 5'-phosphate-modified derivatives of cytochrome c were prepared as described in ref. [24]. Native and modified cytochromes c were reduced with dithionite.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ionic-strength-dependence of the oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by cytochrome c oxidase

Kossekova

Атанасов

Bolli

et al. 1989

Biochemical Journal

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“…In the present study, we have used pyridoxal S'-phosphate (PLP)2 to clarify the interaction between cytochrome P-450scc and adrenodoxin. This reagent has been shown to modify amino groups (e-NH2 group of Lys residues or an a-NH2 group) by forming a Schiff base; reduction of the Schiff base with NaBH4 results in irreversible attachment of PLP to the amino groups (Benesch et al, 1972(Benesch et al, , 1982Aviram & Schejter, 1973;Atanasov et al, 1984;Poulose & Kolattukudy, 1980). Hamamoto and Ichikawa (1984) showed that treatment of adrenodoxin reductase with PLP followed by the NaBH4 reduction caused a selective modification of several Lys residues.…”

mentioning

confidence: 99%

Inhibition of electron transfer from adrenodoxin to cytochrome P-450scc by chemical modification with pyridoxal 5'-phosphate: identification of adrenodoxin-binding site of cytochrome P-450scc

Tsubaki

Iwamoto²,

Hiwatashi³

et al. 1989

Biochemistry

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Covalent modification of cytochrome P-450scc (purified from bovine adrenocortical mitochondria) with pyridoxal 5'-phosphate (PLP) was found to cause inhibition of the electron-accepting ability of this enzyme from its physiological electron donor, adrenodoxin, without conversion to the "P-420" form. Reaction conditions leading to the modification level of 0.82 and 2.85 PLP-Lys residues per cytochrome P-450scc molecule resulted in 60% and 98% inhibition, respectively, of electron-transfer rate from adrenodoxin to cytochrome P-450scc (with beta-NADPH as an electron donor via NADPH-adrenodoxin reductase and with phenyl isocyanide as the exogenous heme ligand of the cytochrome). It was found that covalent PLP modification caused a drastic decrease of cholesterol side-chain cleavage activity when the cholesterol side-chain cleavage enzyme system was reconstituted with native (or PLP-modified) cytochrome P-450scc, adrenodoxin, and NADPH-adrenodoxin reductase. Approximately 60% of the original enzymatic activity of cytochrome P-450scc was protected against inactivation by covalent PLP modification when 20% mole excess adrenodoxin was included during incubation with PLP. Binding affinity of substrate (cholesterol) to cytochrome P-450scc was found to be increased slightly upon covalent modification with PLP by analyzing a substrate-induced spectral change. The interaction of adrenodoxin with cytochrome P-450scc in the absence of substrate (cholesterol) was analyzed by difference absorption spectroscopy with a four-cuvette assembly, and the apparent dissociation constant (Ks) for adrenodoxin binding was found to be increased from 0.38 microM (native) to 33 microM (covalently PLP modified).(ABSTRACT TRUNCATED AT 250 WORDS)

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Charge interactions of cytochrome c with cytochrome c oxidase

Mitovska¹,

Dancheva

Атанасов

1984

International Journal of Biochemistry

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Pyridoxal phosphate modified cytochromes c. Identification and electron transfer properties

Cited by 11 publications

References 28 publications

Ionic-strength-dependence of the oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by cytochrome c oxidase

Ionic-strength-dependence of the oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by cytochrome c oxidase

Inhibition of electron transfer from adrenodoxin to cytochrome P-450scc by chemical modification with pyridoxal 5'-phosphate: identification of adrenodoxin-binding site of cytochrome P-450scc

Charge interactions of cytochrome c with cytochrome c oxidase

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