Introduction to Protein-Ligand Interactions
Protein-Ligand Equilibrium Constants
Protein-Ligand Fractional Saturation
Myoglobin vs. Hemoglobin
Heme Prosthetic Group
Hemoglobin Cooperativity
Hill Equation
Hill Plot
Hemoglobin Binding in Tissues & Lungs
Hemoglobin Carbonation & Protonation
Bohr Effect
BPG Regulation of Hemoglobin
Fetal Hemoglobin
Sickle Cell Anemia
Chymotrypsin's Catalytic Mechanism
Glycogen Phosphorylase
Liver vs Muscle Glycogen Phosphorylase
Motor Proteins
Skeletal Muscle Anatomy
Skeletal Muscle Contraction

Concept #1: Protein-Ligand Equilibrium Constants

Concept #2: Protein-Ligand Dissociation Constant

Practice: Protein A has a binding site for ligand X with a K d of 54 mM. Protein B has a binding site for ligand X with a Kd of 58 mM. Answer the following questions based on this information:

A) Which protein has a stronger affinity for ligand X?

B) Convert the Kd to Ka for both proteins.

Ka for Protein A: __________ 

Ka for Protein B: __________

Practice: You prepare a solution of protein and its ligand where the initial concentrations are [P] = 10 mM and  [L] = 10 mM. At equilibrium you measure the concentration of the complex [PL] = 5 mM. If the protein-ligand reaction can be represented by P + L ⇌ PL, what is the Kd of the reaction under these conditions?