Biochemical and immunological properties of hepatic δ-aminolevulinic acid dehydratase in channel catfish (Ictalurus punctatus)

摘要: Abstract Selective inhibition of mammalian δ-aminolevulinic acid dehydratase (ALAD; porphobilinogen synthetase, EC 4.2.1.24) by Pb serves as a important biological marker chemical exposure and injury. Water-borne has been shown to inhibit ALAD in the blood liver several fish species. This study was undertaken evaluate relative susceptibility hepatic vitro characterize this enzyme determined combination biochemical immunological techniques. The reaction rate assay sensitivity were found increase function temperature duration incubation. results these studies demonstrated that IC 50 (17.3 μM) for activity 40-times higher than those values reported rats (0.31–0.4 μM Pb). Kinetic analyses activities indicated K m 0.043 ± 0.005 mM ALA V max 2.57 0.218 nmol (PBG)/h/mg protein. Further showed no activation Zn only moderate EDTA rat ALAD. Western blot using rabbit polyclonal antibodies directed purified human erythrocyte suggested faint cross-reactivity. These indicate is biochemically distinct from apparently not cofactor and/or binding any metal extremely stable.