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. | 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. | ||
'''Three-dimensional structure of apocalmodulin''' | |||
In the absence of bound Ca2+, the helices of calmodulin pack so that their hydrophobic side chains are not exposed. In this form it is unable to interact with its targets5. | In the absence of bound Ca2+, the helices of calmodulin pack so that their hydrophobic side chains are not exposed. In this form it is unable to interact with its targets5. | ||
(IMAGE CALMODULINE SEULE) | (IMAGE CALMODULINE SEULE) | ||
=Ca2+-bound calmodulin= | =Ca2+-bound calmodulin= | ||