The enzyme works by stepwise addition of pyrrolylmethyl groups until a hexapyrrole is present at the active centre. The terminal tetrapyrrole is then hydrolysed to yield the product, leaving a cysteine-bound dipyrrole on which assembly continues. In the presence of a second enzyme, EC 4.2.1.75 uroporphyrinogen-III synthase, which is often called cosynthase, the product is cyclized to form uroporphyrinogen-III. If EC 4.2.1.75 is absent, the hydroxymethylbilane cyclizes spontaneously to form uroporphyrinogen I.
The enzyme works by stepwise addition of pyrrolylmethyl groups until a hexapyrrole is present at the active centre. The terminal tetrapyrrole is then hydrolysed to yield the product, leaving a cysteine-bound dipyrrole on which assembly continues. In the presence of a second enzyme, EC 4.2.1.75 uroporphyrinogen-III synthase, which is often called cosynthase, the product is cyclized to form uroporphyrinogen-III. If EC 4.2.1.75 is absent, the hydroxymethylbilane cyclizes spontaneously to form uroporphyrinogen I.
uroporphyrinogen III cosynthase is more heat-labile than porphobilinogen deaminase. Heat-treatment of the porphobilinogen deaminase/uroporphyrinogen III cosynthase enzyme system forms only 2-4% of uroporphyrinogen III
erythrocyte enzyme activity in acute intermittent porphyria mice (7.3 pM uroporphyrin/mg hemoglobin) does not improve with bone marrow graft from porphyria mice (5.2 pM uroporphyrin/mg hemoglobin), increases to 12.4 pM uroporphyrin/mg hemoglobin in mice grafted with bone marrow from wild type, wild type has an activity of 16.9 pM uroporphyrin/mg hemoglobin, erythrocyte enzyme deficiency is not associated with acute porphyria, 37°C, phosphate buffered saline
erythrocyte enzyme activity in acute intermittent porphyria mice (7.3 pM uroporphyrin/mg hemoglobin) does not improve with bone marrow graft from porphyria mice (5.2 pM uroporphyrin/mg hemoglobin), increases to 12.4 pM uroporphyrin/mg hemoglobin in mice grafted with bone marrow from wild type, wild type has an activity of 16.9 pM uroporphyrin/mg hemoglobin, erythrocyte enzyme deficiency is not associated with acute porphyria, 37°C, phosphate buffered saline
wild type, lethally irradiated acute intermittent porphyria mice, porphyria mice injected with bone marrow cells from wild type C57BL/6-CD45.1 mice or from acute intermittent porphyria mice
Porphobilinogen deaminase over-expression in hepatocytes, but not in erythrocytes, prevents accumulation of toxic porphyrin precursors in a mouse model of acute intermittent porphyria
J. Hepatol.
52
417-424
2010
Homo sapiens (P08397), Homo sapiens, Mus musculus (P22907), Mus musculus