With the aim to characterize the drastic decrease of Uroporphyrinogen Decarboxylase (Uro-D)activity produced in experimental polyhalogenated aromatic hydrocarbons porphyria, we began to study normal rat liver Uro-D. In order to purify the enzyme, a liver homogenate was subjected to the following purification scheme: centrifugation 20 min at 11,000 x g, supernatant ammonium sulphate precipitation (35-70% sat), phosphate gel absorption, affinity chromatography and gel filtration. We found a complex mixture of proteins exhibiting Uro-D activity. At first we detected two isoforms with MW of 45,000 and 30,000 (IfA and IfB respectively). Trying to further purify IfA by re-cromatography on a G-75 column, we detected a third form of MW 17,000, which appeared in a molecular ratio of about 1:1 respect to IfB. We started the characterization of IfA and IfB, obteining a Km of 0.27 #M and 0.55 p.M for IrA and 5.0 #M and 0.5 #M for IfB, using Uroporphyrinogen III or Pentacarboxyporphyrinogen III as substrate respectively. Besides, we asseyed 2 carboxylic group reagents which showed to have an inhibiting effect on both isoforms, meaning that in the enzymes a carboxyl group would be involved in their active center. This is the first report about 3 hepatic proteins that show Uro-D activity.
Documento: | Artículo |
Título: | Detection and partial characterization of three isoforms of rat liver uroporphyrinogen decarboxylase |
Autor: | Corvi, M.; Guidi, S.; Chaufan, G.; De San Martin Viale, L.; De Rios Molina, M.C. |
Filiación: | Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina |
Año: | 1997 |
Volumen: | 11 |
Número: | 9 |
Título revista: | FASEB Journal |
Título revista abreviado: | FASEB J. |
ISSN: | 08926638 |
CODEN: | FAJOE |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08926638_v11_n9_p_Corvi |