Free radical and electrophilic hydroxylation

Sangster, David F.

doi:10.1002/9780470771259.ch3

Cited by 4 publications

(1 citation statement)

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“…5 The attack of hydroxyl radicals on alkyl carbons is electrophilic, and the predominant reaction is hydrogen abstraction. 6 Thus, hydroxyl radicals could oxidize the methylene bridges of the porphyrinogens to the methene bridges that characterize the porphyrins. By way of analogy, in hepatic cells, iron increases oxidative stress and enhances the oxidation of porphyrinogens to porphyrins.…”

Section: (Am J Pathol 1998 153:703-708)mentioning

confidence: 99%

Porphyrin Loading of Lipofuscin Granules in Inflamed Striated Muscle

Kiefer

McKenney

Trainor

et al. 1998

The American Journal of Pathology

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To further the understanding of oxidative effects on inflammation injury to muscle fiber structure, fluorescent imaging analysis of human striated muscle tissues from a variety of inflammatory or postinflammatory etiologies was undertaken in a search for accumulated coproporphyrin, a red autofluorescent byproduct of heme biosynthesis that would theoretically be formed under oxidative insult. Using a differential excitation method of in situ analysis, porphyrin autofluorescence was detected in intact fibers within the context of the yellow autofluorescent subsarcolemmal lipofuscin granules. Relative measurements of porphyrin concentration in the granules from different patients indicated that the acute/subacute inflammatory specimens grouped significantly higher than the more chronic inflammatory and nonpathological specimens. Myoglobin was also found to be associated with the granules. Myoglobin heme iron could potentially serve as a Fenton reagent for the intracellular generation of hydroxyl radicals, which are responsible for the oxidation of the porphyrinogens. High-performance liquid chromatography analysis of extracted dense particles revealed coproporphyrin as the sole porphyrin present. The observation of coproporphyrin within lipofuscin granules, previously unreported, suggests that lipofuscin accumulation in striated muscle may begin under conditions of acute oxidative stress, as marked by the oxidation of extramitochondrial porphyrinogens that are immediately incorporated into the granules.

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Section: (Am J Pathol 1998 153:703-708)mentioning

confidence: 99%

Porphyrin Loading of Lipofuscin Granules in Inflamed Striated Muscle

Kiefer

McKenney

Trainor

et al. 1998

The American Journal of Pathology

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Iron Enzymes and Models

Marlin

Mascharak

2002

Encyclopedia of Catalysis

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In recent years, iron complexes of designed ligands have been synthesized as mimics of the active sites of the various non‐heme iron enzymes. The reactions of these model complexes have been studied to establish the mechanisms of the enzymatic reactions as well as the identities of the intermediates involved in the biocatalytic processes. The ultimate goal in these endeavors is to isolate functional mimics that could be employed in biomimetic catalysis under mild conditions. This review provides key references to the burgeoning literature on the results of research performed by various groups in the area of oxygen activation, oxygenation of organic substrates, amide hydrolysis, and other useful chemical transformations. Examples of good structural and functional models have been included along with brief descriptions of the enzymes. The role of the coordination spheres of the iron centers and the nature of the key iron‐peroxo and/or hypervalent iron‐oxo intermediates have been discussed. Results of the attempted catalysis by the functional model complexes have also been discussed to highlight the challenge involved in bio‐inspired catalysis as well as the success of the modeling work completed so far.

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