title: In vitro effect of metal ions on the activity of two amphibian glyceraldehyde-3-phosphate dehydrogenases: potential metal binding sites.
abstract: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) was purified from two amphibian species, Xenopus laevis and Pleurodeles waltl. Comparative studies revealed that the two proteins differ by their subunit molecular masses, pI values and V8 digested peptide maps. The effect of zinc, cadmium and copper ions on GAPDH enzymatic activity has been examined in vitro. A time, metal concentration and metal type dependent inhibition was observed for both enzymes. X. laevis and P. waltl GAPDHs exhibit a much greater sensitivity to copper than to cadmium or zinc ions. Different half-lives and differential sensitivity to various metals was observed between the two enzymes with P. waltl GAPDH being remarkably tolerant to cadmium ions compared to the X. laevis enzyme. In order to understand the differential sensitivity of the two enzymes to metals, we produced 3D models of both X. laevis and P. waltl GAPDH structures based upon known 3D structures of GAPDHs from other species. This necessitated, in a first step, to clone a 900 bp cDNA fragment encoding the nearly full-length P. waltl GAPDH. Spatial motif searches on the homology models indicated potential metal binding sites involving cysteine and histidine residues outside the catalytic sites, existing only in either the X. laevis or the P. waltl GAPDH sequences.
authors.affiliation: Laboratoire de Biologie et Physiologie de la Reproduction et du Développement, Faculté des Sciences I, BP. 5366, Maarif, Casablanca, Morocco.
authors.forename: Khadija
authors.initials: K
authors.lastname: Mounaji
authors.forename: Metaxia
authors.initials: M
authors.lastname: Vlassi
authors.forename: Nour-Eddine
authors.initials: NE
authors.lastname: Erraiss
authors.forename: Maurice
authors.initials: M
authors.lastname: Wegnez
authors.forename: Aurelio
authors.initials: A
authors.lastname: Serrano
authors.forename: Abdelaziz
authors.initials: A
authors.lastname: Soukri
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010999:Pleurodeles / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology
chemical_list: D029845:Amphibian Proteins; D018076:DNA, Complementary; D008670:Metals; D002104:Cadmium; D003300:Copper; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D015032:Zinc