BIOC 3560 Lecture Notes - Lecture 4: Cooperative Binding, Dissociation Constant, Conformational Change
25 Sep 2018
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Recall for one site: p + l pl. For a protein with n ligand binding sites . N. b. n = # of sites nh < or = n. Conformational change in one su bunit promotes conformational change in adjacent subunit. Jacques monod, jeffries wyman and jean-pierre changeux (1965) subunits are functionally identical: all subunits change conformation simultaneously subunits can exist in >1 conformation. Sequential model: daniel koshland (1966) ligand binding can induce conformational change in subunit independently. Changed in quaternary structure of hb (t r transition) have dramatic effects on its function as an o2-binding protein the sigmoidal o2-binding curve of hb is diagnostic of cooperative binding. Cooperative binding requires: >1 ligand-binding site, interaction between ligand binding sites. Ph is lower (so h+ is high) and [co2] is high. Hb binds h+ and co2, decreasing affinity for o2 in the capillaries of the lung: Hb releases h+ and co2 increasing affinity for o2.
