Urporphyrinogen Decarboxylase Fron Normal Rat Liver. Purification and Kinetic Studies.

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

Pucón, Chile

Congreso; The Pan-Am Association Biochemistry and Molecular Biology, (VIII PABMB Congress) XXXII Annual Meeting of the Argentinean Siciety of Biochemestry and Molecular Biology of Chile.; 1996

The pan-American Association for Biochemistry and Molecular Biology

Uroporphyrinogen decarboxylase (UroD) is the key enzyme in human and experimental Porphyria Cutanea Tarda. We have completely separated and purified two molecular forms of UroD (SAIB 95). Now we inform its characterization and the detection of a new form. From the (S) vs (S)/v plots the values od Km and Vmax for the different subtrates were calculated and the results obtained are shown in the following table.   ISOFORM MW Uro’gen III Penta’gen III     Km Vmax/Km Km Vmax/Km   (kDa) (mM) (U/mM) (mM) (U/mM) If-a 45 0.27 5.00 0.55 0.87 If-b 30 5.00 1.16 0.50 0.62 IF-c 17 n.d. n.d. n.d. n.d.   It can be seen that the efficiency values for If-a were always higher than those for If-b. This difference was more noticeable ay the Uroporphyrinogen leven. With the If-a we proved that the exist an inverse relation between the activity and the amount of enzyme. If-a and If-b should be the homologous of isoenzymes informed Mukerji and Pinstone (1992) from human eritrocytes. This is the first time that a third UroD isoenzymes could be detected.