Sandbox 213: Difference between revisions

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The affinity of the individual Ca2+ ion binding sites are in the range 10−5-10−6 mol.L−1 and adjacent sites bind Ca2+ with positive cooperativity, so that attachment of the first Ca2+ ion enhances the affinity of its neighbour. This has the effect of making the protein sensitive to small changes in the concentration of Ca2+ within the signaling range.

Ca2+-calmodulin itself has no intrinsic catalytic activity. Its action depends on its close association with a target enzyme.~~</StructureSection>~~

Ca2+-calmodulin itself has no intrinsic catalytic activity. Its action depends on its close association with a target enzyme. The C-terminal domain solution structure is similar while the EF hands of the N-terminal domain are considerably less open. The backbone flexibility within calmodulin is key to its ability to bind a wide range of targets.

Up to four calcium ions are bound by calmodulin via its four EF hand motifs. EF hands supply an electronegative environment for ion coordination. After calcium binding, hydrophobic methyl groups from methionine residues become exposed on the protein via conformational change.

This presents hydrophobic surfaces, which can in turn bind to Basic Amphiphilic Helices (BAA helices) on the target protein. These helices contain complementary hydrophobic regions. The flexibility of Calmodulin's hinged region allows the molecule to "wrap around" its target. This property allows it to tightly bind to a wide range of different target proteins.</StructureSection>

*'''Three-dimensional structure of apocalmodulin'''

Sandbox 213: Difference between revisions

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 The affinity of the individual Ca<sup>2+</sup> ion binding sites are in the range 10<sup>&minus;5</sup>-10<sup>&minus;6</sup> mol.L<sup>&minus;1</sup> and adjacent sites bind Ca<sup>2+</sup> with positive cooperativity, so that attachment of the first Ca<sup>2+</sup> ion enhances the affinity of its neighbour. This has the effect of making the protein sensitive to small changes in the concentration of Ca<sup>2+</sup> within the signaling range.
-Ca<sup>2+</sup>-calmodulin itself has no intrinsic catalytic activity. Its action depends on its close association with a target enzyme.</StructureSection>
+Ca<sup>2+</sup>-calmodulin itself has no intrinsic catalytic activity. Its action depends on its close association with a target enzyme. The C-terminal domain solution structure is similar while the EF hands of the N-terminal domain are considerably less open. The backbone flexibility within calmodulin is key to its ability to bind a wide range of targets.
+Up to four calcium ions are bound by calmodulin via its four EF hand motifs. EF hands supply an electronegative environment for ion coordination. After calcium binding, hydrophobic methyl groups from methionine residues become exposed on the protein via conformational change.
+This presents hydrophobic surfaces, which can in turn bind to Basic Amphiphilic Helices (BAA helices) on the target protein. These helices contain complementary hydrophobic regions. The flexibility of Calmodulin's hinged region allows the molecule to "wrap around" its target. This property allows it to tightly bind to a wide range of different target proteins.</StructureSection>
 *'''Three-dimensional structure of apocalmodulin'''