ChemInform Abstract: REACTIONS OF OXOPHLORINES AND THEIR Π RADICALS

Fuhrhop, J.‐H.; Besecke, S.; Subramanian, J.; Mengersen, Chr.; Riesner, Detlev

doi:10.1002/chin.197607307

Cited by 2 publications

(3 citation statements)

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“…We have reported [24] that under strictly anaerobic conditions employing synthetic α‐hydroxyhaem bound to rat HO‐1 (rHO‐1), this conversion is achieved with an almost equimolar amount of O 2 in the absence of reducing equivalents and that the resultant verdohaem appeared to be in the ferrous state (Scheme 2C). In contrast to the previous studies, the pathway we have proposed does not require any reducing equivalents, and instead postulates generation of an oxidizing equivalent with the formal stoichiometry of (1/2) H 2 O 2 [28].…”

mentioning

confidence: 88%

The reactivity of α‐hydroxyhaem and verdohaem bound to haem oxygenase‐1 to dioxygen and sodium dithionite

Sakamoto

Omata

Hayashi

et al. 2002

European Journal of Biochemistry

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Recently we have shown that ferric α‐hydroxyhaem bound to haem oxygenase‐1 can be converted to ferrous verdohaem by approximately an equimolar amount of O2 in the absence of exogenous electrons [Sakamoto, H., Omata, Y., Palmer, G., and Noguchi, M. (1999) J. Biol. Chem.274, 18196–18200]. Contrary to those results, other studies have claimed that the conversion requires both O2 and an electron. More recently, Migita et al. have reported that the major reaction product of ferric α‐hydroxyhaem with O2 is a ferric porphyrin cation radical that can be converted to ferrous α‐hydroxyhaem with sodium dithionite [Migita, C. T., Fujii, H., Matera, K. M., Takahashi, S., Zhou, H., and Yoshida, T. (1999) Biochim. Biophys. Acta1432, 203–213]. To clarify the reason(s) for the discrepancy, we compared the reactions; i.e. α‐hydroxyhaem to verdohaem and verdohaem to biliverdin, under various conditions as well as according to the procedures of Migita. We find that complex formation of α‐hydroxyhaem with haem oxygenase may be small and a substantial amount of free α‐hydroxyhaem may remain, depending on the reconstitution conditions; this could lead to a misinterpretation of the experimental results. We also find that ferrous verdohaem appears to be air‐sensitive and is therefore easily converted to a further oxidized species with excess O2. Finally, we find that dithionite seems to be inappropriate for investigating the haem oxygenase reaction, because it reduces ferrous verdohaem to a further reduced species that has not been seen in the haem degradation system driven by NADPH‐cytochrome P450 reductase.

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confidence: 88%

The reactivity of α‐hydroxyhaem and verdohaem bound to haem oxygenase‐1 to dioxygen and sodium dithionite

Sakamoto

Omata

Hayashi

et al. 2002

European Journal of Biochemistry

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“…The electrochemical reduction of [ZnOEOP] + 164 occurred irreversibly at +0.17 V (vs SCE) in CH 2 Cl 2 with TBAP. 267 However, in the presence of a base, electrochemical reduction of 164 occurred at −0.29 V, indicating the extremely high electron affinity of the oxoniaporphyrin π-system. 267 Indeed, these electron-deficient porphyrins reacted with a variety of different nucleophiles, including alcohols, amides, hydroxide, cyanide, and even DMF under mild conditions to yield the corresponding ring-opened, α-functionalized helical tetrapyrrole derivatives.…”

Section: Oxa-and Thiaporphyrins and Related Compoundsmentioning

confidence: 99%

“…267 However, in the presence of a base, electrochemical reduction of 164 occurred at −0.29 V, indicating the extremely high electron affinity of the oxoniaporphyrin π-system. 267 Indeed, these electron-deficient porphyrins reacted with a variety of different nucleophiles, including alcohols, amides, hydroxide, cyanide, and even DMF under mild conditions to yield the corresponding ring-opened, α-functionalized helical tetrapyrrole derivatives. 270 The research groups of Balch and Mizutani independently studied the mechanism responsible for the ringopening reactions of these meso-oxaporphyrin systems and concluded that these reactions involved nucleophile attack at the α carbon adjacent to the meso oxygen atom, followed by the cleavage of the C−O bond.…”

Section: Oxa-and Thiaporphyrins and Related Compoundsmentioning

confidence: 99%

Synthesis of Aza-, Oxa-, and Thiaporphyrins and Related Compounds

Matano

2016

Chem. Rev.

112

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Chemical modification at the periphery with nitrogen or chalcogens is a highly promising strategy to diversify the optical, electrochemical, magnetic, and coordination properties of the porphyrin family. Indeed, various kinds of phthalocyanines and related benzo-annelated azaporphyrinoids have been synthesized, and their fundamental properties have been extensively investigated. However, the synthesis of heteroatom-containing porphyrins in which the peripheral methine groups are partially replaced with nitrogen or chalcogens remains a considerable challenge. In this review, we will focus mainly on recent advances in the synthesis of aza-, oxa-, and thiaorphyrins and related compounds, including historically important examples.

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ChemInform Abstract: REACTIONS OF OXOPHLORINES AND THEIR Π RADICALS

Abstract: Die Oxidation des Oxophlorins (I) mit z‐.

Cited by 2 publications

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The reactivity of α‐hydroxyhaem and verdohaem bound to haem oxygenase‐1 to dioxygen and sodium dithionite

The reactivity of α‐hydroxyhaem and verdohaem bound to haem oxygenase‐1 to dioxygen and sodium dithionite

Synthesis of Aza-, Oxa-, and Thiaporphyrins and Related Compounds

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