Disturbances on delta aminolevulinate dehydratase (ALA-D) enzyme activity by Pb2+, Cd2+, Cu2+, Mg2+, Zn2+, Na+, K+ and Li+: analysis based on coordination geometry and acid-base Lewis capacity
| Autor: | N.L. Pauza, A. M. Ferramola de Sancovich, M.J. Pérez Cotti, L. Godar, H.A. Sancovich |
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| Rok vydání: | 2004 |
| Předmět: |
inorganic chemicals
Stereochemistry Allosteric regulation Chick Embryo In Vitro Techniques Biochemistry Cofactor Enzyme catalysis Inorganic Chemistry Enzyme activator Cations Animals Enzyme Inhibitors Schiff Bases Coordination geometry Yolk Sac chemistry.chemical_classification biology Chemistry Porphobilinogen Synthase Enzyme assay Enzyme structure Enzyme Activation Enzyme Liver Metals biology.protein |
| Zdroj: | Journal of inorganic biochemistry. 99(2) |
| ISSN: | 0162-0134 |
| Popis: | ALA-D (EC 4.2.1.24) is the first cytosolic enzyme in the haem metabolic pathway. Some metals compete with its major cofactor Zn(2+), modifying both enzyme structure and function. Our purpose was to contribute to the understanding of the biochemical role of metals such as Pb(2+), Cd(2+), Cu(2+), Mg(2+), Zn(2+), Na(+), K(+) and Li(+) on ALA-D, using chicken embryos as experimental model. Mg(2+) and Zn(2+) showed enzyme activation in yolk sac membrane (YSM) (113% at 10(-5) M Mg(2+) and from 10(-4) M Zn(2+)), and slight inactivation in liver. Cd(2+) and Cu(2+) caused a non allosteric inhibition in both tissues (100% from 10(-4) M). Surprisingly Pb(2+) was not such a strong inhibitor. Interference of cations during the Schiff base formation in enzymatic catalysis process is explained considering their Lewis acid-base capacity, coordination geometry and electron configuration of valence. Interactions among monovalent cations and biochemical substances are governed chiefly by its electrostatic potential. 0.1 M K(+) and 0.4 M Na(+) produced 30% of enzymatic inhibition by the interference on interactions among the functional subunits. Li(+) activated the YSM enzyme (130% at 10(-5) M) due to a more specific interaction. This study may contribute to elucidate for the first time the possible structural differences between the YSM and liver enzymes from chicken embryo. |
| Databáze: | OpenAIRE |
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