Final answer:
To determine the fraction of bound versus unbound binding partners, establish a relationship between the dissociation constant (Kd), the concentrations of the binding partners, and the concentration of the bound complex using mass action law.
Step-by-step explanation:
The dissociation constant (Kd) value of 10E-9M for a binding interaction and the concentration of binding partners at 10E-7M suggest that the next step is to determine the fraction of bound versus unbound partners. One could use the law of mass action to establish the relationship between Kd, the concentrations of the binding partners, and the bound complex concentration. It typically involves setting up an equation that reflects the equilibrium condition, which would be Kd = [free receptor][free ligand] / [receptor-ligand complex]. Then, you would rearrange the variables to solve for the concentration of the bound complex ([receptor-ligand complex]).