Figure 1.
Original figure from Christian Bohr [1], showing the sigmoidal increase of oxyhemoglobin as a function of the partial pressure of oxygen.
Figure 2.
Hill plot of the Hill equation in red, showing the slope of the curve being the Hill coefficient and the intercept with the x-axis providing the apparent dissociation constant.
The green line shows the noncooperative curve.
Figure 3.
Reaction scheme of a Monod-Wyman-Changeux model of a protein made up of two protomers.
The protomer can exist under two states, each with a different affinity for the ligand. L is the ratio of states in the absence of ligand, c is the ratio of affinities.
Figure 4.
Energy diagram of a Monod-Wyman-Changeux model of a protein made up of two protomers.
The larger affinity of the ligand for the R state means that the latter is preferentially stabilised by the binding.
Figure 5.
Hill plot of the MWC binding function in red, of the pure T and R state in green.
As the conformation shifts from T to R, so does the binding function. The intercepts with the x-axis provide the apparent dissociation constant as well as the microscopic dissociation constants of the R and T states.
Figure 6.
Cartoon representation of the protein hemoglobin in its two conformations: “tensed (T)” on the left corresponding to the deoxy form (derived from Protein Data Bank entry 1LFL) and “relaxed (R)” on the right corresponding to the oxy form (derived from Protein Data Bank entry 1LFT).
Alpha globins are red and green, while beta globins are yellow and orange.
Figure 7.
Cartoon representation of the protein calmodulin in its two conformations: “closed” on the left (derived from PDB id: 1CFD) and “open” on the right (derived from PDB id: 3CLN).
The open conformation is represented bound with 4 calcium ions (orange spheres).