Factors affecting the line-shape of the EPR signal of high-spin Fe(III) in soybean lipoxygenase-1

Slappendel, Steven; Aasa, Roland; Malmström, Bo G.; Verhagen, Jan; Veldink, Gerrit A.; Vliegenthart, Johannes F.G.

doi:10.1016/0167-4838(82)90435-6

Cited by 42 publications

(38 citation statements)

References 17 publications

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“…In contrast, both lipoxygenases as isolated from large immature seeds (lane 3, Figure 1, 417 mg average) had epr signals in their spectra with g values around 6 (traces A and B). Both signals were similar to those previously reported for the type-1 enzyme from soybeans which had been oxidized by the product ofthe catalytic process, 1 3-hydroperoxy-9(Z),1 I(E)-octadecadienoic acid (16 In vitro Iron Incorporation. As a test of the de novo synthesis of lipoxygenase under tissue culture conditions, immature seeds were grown in medium which was supplied with iron chelate enriched in the gamma emitting isotope, iron-59.…”

supporting

confidence: 75%

“…The signal in the spectrum at g6 from immature seed lipoxygenases had the same characteristics as the signal obtained from the mature seed enzyme after treatment with the hydroperoxide product of the reaction (16). This has been previously interpreted as an oxidation of the native enzyme, an epr silent iron(II) species, to an active high spin iron(III) enzyme by the hydroperoxide (16). The presence of an active, iron(III) lipoxygenase in the fresh tissue and only reduced material in the mature seed implies that the enzyme undergoes a reduction process as the seed dries.…”

Section: Discussionmentioning

confidence: 55%

“…The Figure 5. As has been previously reported (16), the type-l enzyme from mature seeds had no signal in its spectrum (trace C). This has been taken as an indication that the enzyme is present in soybeans as the epr silent high spin iron(II) form.…”

mentioning

confidence: 57%

“…A large monomeric protein (95 kD), the type-1 lipoxygenase from soybeans is a nonheme iron dioxygenase. Epr9 spectroscopy indicates that the iron atom plays a redox role in the catalytic mechanism of this enzyme cycling between iron(III) and iron(II) states as the substrate is first oxidized to a carbon centered radical and the subsequently formed peroxy radical is reduced to the corresponding hydroperoxide (16). Interestingly, the enzyme as it is isolated from mature seeds contains iron(II) and must be activated to the iron(III) state through oxidation by the product of its catalysis.…”

mentioning

confidence: 99%

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The Lipoxygenases in Developing Soybean Seeds, Their Characterization and Synthesis in Vitro

Funk

Carroll²,

Thompson³

et al. 1986

Plant Physiol.

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A number of lipoxygenase isoenzymes were identified in developing soybean (Glycine max L. Merrill cv Provar) seeds and two have been partially characterized. In a study of lipoxygenase level in developing soybean seeds, the enzyme content increased markedly during development. Comparisons of the lipoxygenases from mature soybean seeds and immature seeds by isoelectric focusing, chromatofocusing, sodium dodecyl sulfate polyacrylamide gel electrophoresis and peptide mapping identified two categories of isoenzyme. The isoenzymes from immature seeds were found by electron paramagnetic resonance spectroscopy to be isolated at least in part as the high spin iron(III) or active form of the enzyme in contrast to lipoxygenases from mature seeds which were isolated as electron paramagnetic resonance silent, high spin iron(II) species. The discovery of increased levels of lipoxygenases during seed development and their isolation in an active form suggests that the enzyme may play a physiological role during the maturation process. The incorporation of iron-59 from the nutrient medium into lipoxygenase during culture of immature seeds was indicative of de novo synthesis of the enzyme. The efficiency of the iron uptake was high, as indicated by the level of radioactivity found in the enzyme (one gram atom of iron per mole of lipoxygenase).

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supporting

confidence: 75%

Section: Discussionmentioning

confidence: 55%

mentioning

confidence: 57%

mentioning

confidence: 99%

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The Lipoxygenases in Developing Soybean Seeds, Their Characterization and Synthesis in Vitro

Funk

Carroll²,

Thompson³

et al. 1986

Plant Physiol.

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“…complex EPR signal around g 6 [2][3][4] arising from at least three high-spin Fe(III) species [5] differing in their degree of rhombicity [6].…”

Section: Introductionmentioning

confidence: 99%

1H-NMR spectroscopic study on the binding of alcohols to soybean lipoxygenase-1

Slappendel

Aasa

Falk

et al. 1982

Biochimica et Biophysica Acta (BBA) - Protein Structure and Mol

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The line-shape of the EPR signal around g 6 of yellow lipoxygenase-l, obtained upon addition of I molar equivalent of 13-Ls-hydroperoxy-9-cis, ll-trans-octadecadienoic acid to the native enzyme (linoleate:oxygen oxidoreductase, EC 1.13.11.12), is strongly affected by alcohols. NMR spectra of solutions of alcohols to which lipoxygenase has been added show a line-broadening of the proton resonances which is due to proton relaxation enhancement from magnetic interaction between iron and protons. This can be taken as direct evidence for binding of alcohols in the vicinity of iron. For unbranched alcohols the line-broadening gradually increases, going from the methyl protons to the protons on carbon atom I, indicating that the latter are closer to iron. Titrations of yellow lipoxygenase with ethanol, 1-butanol and l-bexanol reveal that the affinity of the alcohols increases with longer carbon chain length; their binding constants were found to be 260, 30 and approx. 3 mM, respectively. The distances between protons of bound alcohol and iron were calculated with the Solomon-Bloembergen equation, leading to values of approx. 6 h, for the distance between iron and the methyl protons. A hydrophobic binding of the alcohols to the enzyme is proposed in line with the mode of binding of the natural substrates, polyunsaturated fatty acids.

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Enzymology and Physiology of Reticulocyte Lipoxygenase: Comparison with Other Lipoxygenases

Schewe

Rapoport

Kühn

1986

Advances in Enzymology - And Related Areas of Molecular Biology

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Factors affecting the line-shape of the EPR signal of high-spin Fe(III) in soybean lipoxygenase-1

Cited by 42 publications

References 17 publications

The Lipoxygenases in Developing Soybean Seeds, Their Characterization and Synthesis in Vitro

The Lipoxygenases in Developing Soybean Seeds, Their Characterization and Synthesis in Vitro

1H-NMR spectroscopic study on the binding of alcohols to soybean lipoxygenase-1

Enzymology and Physiology of Reticulocyte Lipoxygenase: Comparison with Other Lipoxygenases

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