title: Purification and properties of uroporphyrinogen III synthase (co-synthetase) from Euglena gracilis.
abstract: Uroporphyrinogen III synthase (co-synthetase) purified from Euglena gracilis is a monomer of Mr 38 500 by gel-filtration studies and 31 000 by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The pI is apparently in the range 4.8-5.1. No evidence for any cofactors was found, and folate derivatives were shown to be absent; no metal ions appear to be present in the enzyme. The Km for hydroxymethylbilane is in the range 12-40 microM, and the product, uroporphyrinogen III, is an inhibitor. Modification studies suggest that arginine residues are essential for the activity of co-synthetase; lysine residues may also be essential, but histidine, cysteine and tyrosine residues are not.
mesh_terms: D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D004852:Epoxy Compounds / Q000494:pharmacology; D005056:Euglena gracilis / Q000201:enzymology*; D006836:Hydro-Lyases / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008970:Molecular Weight; D010658:Phenylglyoxal / Q000494:pharmacology; D011165:Porphyrinogens / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D012395:Rose Bengal / Q000494:pharmacology; D014576:Uroporphyrinogen III Synthetase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D014577:Uroporphyrinogens / Q000378:metabolism*
chemical_list: D004852:Epoxy Compounds; D011165:Porphyrinogens; D014577:Uroporphyrinogens; D012395:Rose Bengal; D011732:Pyridoxal Phosphate; C007366:diepoxybutane; D006836:Hydro-Lyases; D014576:Uroporphyrinogen III Synthetase; D004047:Diethyl Pyrocarbonate; D010658:Phenylglyoxal