Selective metal ion binding at the calcium-binding sites of the sea urchin extraembryonic coat protein hyalin.
The interaction of metal ions with the sea urchin extraembryonic coat protein hyalin was investigated. Hyalin, immobilized on nitrocellulose membrane, bound Ca2+ and this interaction was disrupted by ruthenium red and selective metal ions. The divalent cations Cd2+ and Mn2+, when present at a concentration of 30 microM, displaced hyalin-bound Ca2+. In competition assays, 1 mM Cd2+ or 3 mM Mn2+ were effective competitors with Ca2+ for binding to hyalin. Cobalt, at a concentration of 30 microM, was unable to displace protein-bound Ca2+, but was effective in competition assays at a concentration of at least 10 mM. Magnesium and the monovalent cation Cs+ were unable to disrupt Ca2(+)-hyalin interaction. Interestingly, Cd2+, Mn2+, and Co2+ mimicked the biological effects of Ca2+ on the hyalin self-association reaction. These results clearly demonstrate that the Ca2(+)-binding sites on hyalin can selectively accommodate other divalent cations in a biologically active configuration.
Robinson
J J
JJ
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada.
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D006818:Hyalin / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D011485:Protein Binding; D012617:Sea Urchins / Q000196:embryology* / Q000378:metabolism
D002132:Calcium Radioisotopes; D008670:Metals; D002118:Calcium