title: Involvement of free and enzyme-bound intermediates in the reaction mechanism catalyzed by the bovine liver immobilized porphobilinogen deaminase. Proof that they are substrates for cosynthetase in uroporphyrinogen III biosynthesis.
abstract: The detection and accumulation of tetrapyrrole intermediates synthesized by the action of bovine liver porphobilinogen deaminase immobilized to Sepharose 4B is reported. Employing Sepharose-deaminase preparations, two phases in uroporphyrinogen I synthesis as a function of time were observed, suggesting the accumulation of free and enzyme-bound intermediates, the concentration and distribution of which were time dependent. The deaminase-bound intermediate behaves as a substrate in uroporphyrinogen I synthesis whereas the free intermediates produce enzyme inhibition. The tetrapyrrole intermediate bound to the Sepharose-enzyme is removed from the protein by the binding of porphobilinogen. Free as well as enzyme-bound intermediates are shown to be substrates for cosynthetase with formation of 80% uroporphyrinogen III.
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias, CIPYP (FCEN, UBA-CONICET), Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: M L
authors.initials: ML
authors.lastname: Kotler
authors.forename: A A
authors.initials: AA
authors.lastname: Juknat
authors.forename: S A
authors.initials: SA
authors.lastname: Fumagalli
authors.forename: A M
authors.initials: AM
authors.lastname: Batlle
mesh_terms: D000818:Animals; D001709:Biotechnology; D002417:Cattle; D004800:Enzymes, Immobilized; D011163:Hydroxymethylbilane Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D013379:Substrate Specificity; D014577:Uroporphyrinogens / Q000096:biosynthesis*
chemical_list: D004800:Enzymes, Immobilized; D014577:Uroporphyrinogens; D011163:Hydroxymethylbilane Synthase