Single amino acid substitutions in the Ca2+-binding site of recoverin.II.The unusual behavior of the protein upon the binding of calcium ions |
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Authors: | Uverskiĭ V N Permiakov S E Senin I I Cherskaia A M Shul'ga-Morskoĭ S V Zinchenko D V Alekseev A M Zargarov A A Lipkin V M Filippov P P Permiakov E A |
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Institution: | Institute for Biological Instrument Making, Russian Academy of Sciences, Pushchino, Russia. |
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Abstract: | The structural properties of myristoylated forms of recombinant recoverin of the wild type and of its mutants with damaged second and/or third Ca(2+)-binding sites were studied by fluorimetry and circular dichroism. The interaction of wild-type recoverin with calcium ions was shown to induce unusual structural rearrangements in its molecule. In particular, protein binding with Ca2+ ions results in an increase in the mobility of the environment of Trp residues, in higher hydrophobicity, and in elevated thermal stability (its thermal transition shifts by 15 degrees C to higher temperatures) but has almost no effect on its secondary structure. Similar structural changes induced by Ca2+ are also characteristic of the -EF2 mutant of recoverin whose second Ca(2+)-binding site is modified and cannot bind calcium ions. The structural properties of the -EF3 and -EF2,3 mutants (whose third or simultaneously second and third Ca(2+)-binding sites, respectively, are modified and damaged) are practically indifferent to calcium ions. |
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