Chromatographic behaviour of tree proteins with uroporphyrinogen decarboxylase activity and early studies of characterization.

RÍOS DE MOLINA M. C.,; CORVI M.,; CHAUFAN G.,; GUIDI S.,; TAMINELLI G.,; PAVETO C.,; SAN MAERTÍN DE VIALE L. C.

Hamburgo, Alemania

Congreso; 10th Symposium on Molecular Biology of Hematopoiesis.; 1997

Acta haematologica

Uroporphyrinogen decarboxylase (UroD) is the fifth enzyme of the haem metabolic pathway. Its activity is drastically decreased both in human and experimental Porphyria Cutanea Tarda. In spite of its importance, little is know about its struture and reaction mechanism. Trying to bring light to both aspect, last year we have detect 2 hepatic isoforms, that we named IfA (MW 45,000) and IfB (MW 30,000). Following with the characterization of these isoforms, we have begun studies using different effectors. Treatments with bivalent metals (Zn++,Cu++, and Hg++) showed an inhibitory effect of IfA. Preliminary studies with the liver UroD from hexachlorobenzene porphyric rat allow to demonstrated inhibitory effect of the above mentioned metals. Besides, we have detected another form of UroD, eluted from a re-cromatography of IfA on Sephadex G-75 column, named by us IfC. IfC has a molecular weight of 17,000 and appears in a molecular ratio of about 1:1 when compared with IfB. This is a first report about a protein of low molecular weight exhibiting UroD activity. Preliminary genetic studies by Northen blot let us detect 3 positive bands reveled with a human UroD cDNA (gently supplied by Dr. de Verneuil) marked with 32P. This led us to think that IfA, IfB and IfC might be 3 UroD isoenzymes.