Linked Life Data

1159079

Source:http://linkedlifedata.com/resource/pubmed/id/1159079

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1975-12-4
pubmed:abstractText
Porphria cutanea tarda is characterized biochemically by excessive hepatic synthesis and urinary excretion of uroporphyrin I and 7-carboxylporphyrins. This pattern of excretion suggest an impaired ability to decarboxylate uroporphyrinogen to the paired ability to decarboxylate uroporphyringen to the 4-carboxyl porphyrinogen, coproporphyrinogen, a reaction catalyzed by the enzyme uroporphyringen decarboxylase. 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 procine 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 1.5 N HCl 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 scinllation 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. Ortholpehanthroline 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.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-13549492, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-14023095, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-14110503, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-14110508, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-14461826, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-14907713, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-4117946, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-4191620, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-4640947, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-4749164, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-4785438, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5140185, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5150295, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5416593, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5435226, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5470740, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5473577, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5507243, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5573362, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5823493, http://linkedlifedata.com/resource/pubmed/commentcorrection/1159079-5833390
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9738
pubmed:author
pubmed:issnType
Print
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
661-7
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1975
pubmed:articleTitle
The role of iron in the pathogenesis of porphyria cutanea tarda. II. Inhibition of uroporphyrinogen decarboxylase.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.