title: delta-Aminolevulinic acid dehydratase inactivation by uroporphyrin I in light and darkness.
abstract: 1. The action of uroporphyrin I on erythrocytic ALA-D activity under dark and light conditions was examined. 2. Photo and non-photoinactivation of ALA-D induced by uroporphyrin I were observed. 3. Both effects were dependent on uroporphyrin concentration, temperature and time of exposure of the protein to the porphyrin. 4. Light-dependent effect of uroporphyrin I is related with the phototoxicity of porphyrins and could be produced by primary amino acid photooxidation followed by secondary cross-linking of the protein. 5. Light-dependent effect of uroporphyrin I could be ascribed to a direct enzyme inhibition due to binding of the porphyrin to the protein inducing structural changes at or near its active site.
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), University of Buenos Aires, Argentina.
authors.forename: S G
authors.initials: SG
authors.lastname: Afonso
authors.forename: S
authors.initials: S
authors.lastname: Chinarro
authors.forename: R
authors.initials: R
authors.lastname: Enriquez de Salamanca
authors.forename: A M
authors.initials: AM
authors.lastname: Batlle
mesh_terms: D003624:Darkness; D006801:Humans; D008027:Light; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors*; D013696:Temperature; D014578:Uroporphyrins / Q000494:pharmacology*
chemical_list: D014578:Uroporphyrins; C034103:uroporphyrin I; D000623:Porphobilinogen Synthase