Uroporphyrinogen I synthase from human erythrocytes: separation, purification, and properties of isoenzymes.

Purification and properties of uroporphyrinogen I synthase from human erythrocytes. Identification of stable enzyme-substrate intermediates.

Purification and properties of uroporphyrinogen III synthase from human erythrocytes.

Uroporphyrinogen III synthase (hydroxymethylbilane hydro-lyase (cyclizing); EC 4.2.1.75), the fourth enzyme in the heme biosynthetic pathway, was purified to homogeneity from human erythrocytes. For enzyme purification and characterization, a sensitive coupled enzyme assay was used which generated the substrate, hydroxymethylbilane; the oxidized product, uroporphyrin III, was quantitated by hig...

The UPS locus encoding uroporphyrinogen I synthase is located on human chromosome 11.

The expression of the UPS locus encoding uroporphyrinogen I synthase has been investigated in human/mouse somatic cell hybrids. Human and mouse uroporphyrinogen I synthase can be readily distinguished by their isoelectric points. In hybrid cells, both human and mouse isozymes are detected. The multiple human uroporphyrinogen I synthase isozymes segregate as a single unit, as expected if they ar...

Decreased red cell uroporphyrinogen I synthetase activity in intermittent acute porphyria.

Intermittent acute porphyria has recently been distinguished biochemically from other genetic hepatic porphyrias by the observation of diminished hepatic uroporphyrinogen I synthetase activity and increased delta-aminolevulinic acid synthetase activity. Since deficient uroporphyrinogen I synthetase may be reflected in nonhepatic tissues, we have assayed this enzyme in red cell hemolysates from ...

Direct assay of enzymes in heme biosynthesis for the detection of porphyrias by tandem mass spectrometry. Porphobilinogen deaminase.

We report a new assay of human porphobilinogen deaminase (PBGD). Deficiency in this enzyme activity causes acute intermittent porphyria, the most common disorder of heme biosynthesis. The assay involves incubation of blood erythrocyte lysate with porphobilinogen, the natural PBGD substrate. Two subsequent enzymes in the heme biosynthetic pathway, uroporphyrinogen III synthase and uroporphyrinog...