Isolation and characterization of two isoforms of the hepatic uroporphyrinogen decarboxylase.

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

York, Inglaterra.

Congreso; Tetrapyrrol Discussion Group Meeting. Biochemical and Chemical Aspect of Tetrapyrroles; 1996

Universidad de York

Two molecular forms (MW 54,000 kD: IfA and MW 30 kD: IfB) of Uroporphyrinogen decarboxylase (URO-D) were separated and purified from rat liver using either uroporphyrinogen I or III as substrates. Both of them were inhibited by N-etyl-5-phenylisoxazolium-3’-sulphate and 1-cyclohexyl-3-(2-morpholino-ethyl)-carbodiimide-metho-p-toluensulfonate, indicating that carboxyl group are involving in the URO-D catalysis. The activation energy of Ifa is lower than that od the IfB. Kinetic studies, with uro or pentacarboxyporphyrinogen III as substrates showed that the efficiency of IfA was always higher than that for IfB. This is the first time that two forms of hepatic rat URO-D were reported.