title: Biosynthesis of porphyrins in Rhodopseudomonas palustris--VI. The effect of metals, thiols and other reagents on the activity of uroporphyrinogen decarboxylase.
abstract: The effect of several metals and reagents on the decarboxylation rate of uroporphyrinogen I by using a 16-fold purified preparation of Uroporphyrinogen Decarboxylase from Rhodopseudomonas palustris, was studied. 1 mM Hg2+ and Cu2+ were strong inhibitors, 1 mM Zn2+ and Fe2+ under certain conditions and 1 mM Fe3+ and Cr3+ also inactivated the enzyme, but Pb2+, Cd2+ and Al3+ did not. Metals inhibition was reversed by 1 mM GSH or CySH. 0.1 mM DTNB and PCMB, 1 mM pyridoxal phosphate and 100 mM chloral hydrate, as well as 1 mM 2-methoxy-5-nitrotropone and 0.2 mM diethylpyrocarbonate inhibited Uroporphyrinogen Decarboxylase; while GSH, CySH, N-ethylmaleimide, sodium thioglycolate, 1,4-dithioerythritol, EDTA and O-phenantroline did not modify activity. Data obtained would indicate that one cysteine, one or two histidine residues and probably a lysine group are required for enzyme activity.
mesh_terms: D002262:Carboxy-Lyases / Q000378:metabolism*; D002729:Chloromercuribenzoates / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology; D008628:Mercury / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D011166:Porphyrins / Q000096:biosynthesis*; D012241:Rhodopseudomonas / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000494:pharmacology*; D014575:Uroporphyrinogen Decarboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology; D020245:p-Chloromercuribenzoic Acid
chemical_list: D002729:Chloromercuribenzoates; D005296:Ferrous Compounds; D008670:Metals; D011166:Porphyrins; D013438:Sulfhydryl Compounds; D020245:p-Chloromercuribenzoic Acid; D003300:Copper; D004228:Dithionitrobenzoic Acid; D002262:Carboxy-Lyases; D014575:Uroporphyrinogen Decarboxylase; D008628:Mercury; D015032:Zinc