A qualitative and quantitative study of the separation of uroporphyrin octamethyl esters I and III by dioxan chromatography

Cornford, Pamela; Benson, Amy

doi:10.1016/s0021-9673(01)92287-3

Cited by 52 publications

(20 citation statements)

References 18 publications

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“…In these experiments, [8H] UROGEN I was utilized as the substrate and the reaction products were quantitated spectrophotometrically in HCl, esterified, and chromatographed on paper (19). The radioactivity of the fluorescent spots was determined and the amount of decarboxylated product formed was calculated.…”

Section: Resultsmentioning

confidence: 99%

“…The porphyrin methyl esters were transferred to chloroform and identified chromatographically either on Whatman no. 1 paper by the method of Cornford and Benson (19) or on silica gel thin-layer cards (DC-Karten SI, Riedel-DeHaen AG, Hanover, Germany) developed with the benzene-ethyl acetate-methanol system of Doss (20). The fluorescent spots on the developed paper chromatograms were eluted with chloroform and the radioactivity determined in Permaflour (Packard Instrument 'Levin, E. Y.…”

Section: Introductionmentioning

confidence: 99%

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The role of iron in the pathogenesis of porphyria cutanea tarda. II. Inhibition of uroporphyrinogen decarboxylase.

Kushner¹,

Steinmüller²,

Lee³

1975

J. Clin. Invest.

127

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A B S T R A C T Porphyria cutanea tarda is characterized biochemically by excessive hepatic synthesis and urinary excretion of uroporphyrin I and 7-carboxyl porphyrins. This pattern of excretion suggests an impaired ability to decarboxylate uroporphyrinogen to the 4-carboxyl porphyrinogen, coproporphyrinogen, a reaction catalyzed by the enzyme uroporphyrinogen de-carboxylase.Because clinical evidence has implicated iron in the pathogenesis of porphyria cutanea tarda, these experiments were designed to study the effect of iron on uroporphyrinogen decarboxylase in porcine crude liver extracts.Mitochondria-free crude liver extracts were preincubated with ferrous ion and aliquots were assayed for uroporphyrinogen decarboxylase activity. Uroporphyrinogens I and III, the substrates for the decarboxylase assay, were prepared enzymatically from [3H]porphobilinogen. The products of the decarboxylase reaction were identified and quantitated by three methods: (a) extraction into ethyl acetate at pH 4.0, back extraction into 1.5 N HCO and spectrophotometric quantitation; (b) adsorption onto talc, esterification, paper chromatographic identification, and quantitation by liquid scintillation counting; and (c) adsorption onto talc, esterification, thin-layer chromatographic identification on silica gel, and quantitation by liquid scintillation counting. The thin-layer scintillation method proved most sensitive as it was the only method which accurately identified and quantitated the 7-carboxyl porphyrin reaction product. Uroporphyrinogens I and III were decarboxylated at the same rate by porcine hepatic uroporphyrinogen decarboxylase, and the addition of iron induced marked inhibition of the decarboxylase activity. Orthophenanthroline blocked the inhibitory effect of iron.The inhibition of uroporphyrinogen decarboxylase by ferrous ion, coupled with its previously reported inhibitory effect on uroporphyrinogen III cosynthetase, provides a possible biochemical explanation for the pattern of urinary porphyrin excretion observed in patients with porphyria cutanea tarda and the clinical association with disordered iron metabolism.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of iron in the pathogenesis of porphyria cutanea tarda. II. Inhibition of uroporphyrinogen decarboxylase.

Kushner¹,

Steinmüller²,

Lee³

1975

J. Clin. Invest.

127

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“…With paper chromatography (24), uroporphyrin was detected in incubations containing ferritin and cysteine whereas none was visible in those without these additives. With increasing ferritin concentrations, the uroporphyrin I levels increased and coproporphyrin III levels decreased, as estimated by the intensity of fluorescence of the spots on chromatograms.…”

Section: Resultsmentioning

confidence: 95%

The Role of Iron in the Pathogenesis of Porphyria Cutanea Tarda

Kushner¹,

Lee²,

Nacht³

1972

J. Clin. Invest.

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“…In addition, the material behaves like uroporphyrin on chromatography in lutidine-ammonia (18). After esterification, it has the chromatographic properties of uroporphyrin methyl ester in dioxanekerosene (21). Chromatography (18) after decarboxylation to coproporphyrin (17) showed that it consists of more than 90% isomer I.…”

Section: Methodsmentioning

confidence: 99%

Erythropoietic Porphyria of the Fox Squirrel Sciurus niger

Levin¹

1973

J. Clin. Invest.

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A qualitative and quantitative study of the separation of uroporphyrin octamethyl esters I and III by dioxan chromatography

Cited by 52 publications

References 18 publications

The role of iron in the pathogenesis of porphyria cutanea tarda. II. Inhibition of uroporphyrinogen decarboxylase.

The role of iron in the pathogenesis of porphyria cutanea tarda. II. Inhibition of uroporphyrinogen decarboxylase.

The Role of Iron in the Pathogenesis of Porphyria Cutanea Tarda

Erythropoietic Porphyria of the Fox Squirrel Sciurus niger

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