Chapter 5, Problem 2P

(a)

Summary Introduction

To determine: The situation in which a protein has multiple subunits, each with a single ligand-binding site. Binding to one site decreases the binding affinity of other sites for the ligand.

Introduction:

The cooperative binding of oxygen to the hemoglobin was first described by Archibald Hill in 1910. The cooperative binding of oxygen to Hb is a form of allosteric binding in which the binding of one ligand (oxygen) affects the binding affinities of other remaining binding sites of the receptor molecule. The measure of the degree of cooperativity is denoted by n_H, the Hill coefficient. If n_H is equal to 1, the binding of ligand is not cooperative, if n_H is greater than 1, the ligand binding indicates positive cooperativity, and if n_H is less than 1 the ligand binding indicates the negative cooperativity. The plotting of hill equations on a plot of log Y versus log L is called a Hill plot.

Summary Introduction

(b)

To determine: The situation in which a protein is a single polypeptide with two ligand-binding site, each having a different affinity for the ligand.

Introduction:

The cooperative binding of oxygen to the hemoglobin was first described by Archibald Hill in 1910. The cooperative binding of oxygen to Hb is a form of allosteric binding in which the binding of one ligand (oxygen) affects the binding affinities of other remaining binding sites of the receptor molecule. The measure of the degree of cooperativity is denoted by n_H, the Hill coefficient. If n_H is equal to 1, the binding of ligand is not cooperative, if n_H is greater than 1, the ligand binding indicates positive cooperativity, and if n_H is less than 1 the ligand binding indicates the negative cooperativity. The plotting of hill equations on a plot of log Y versus log L is called a Hill plot.

Summary Introduction

(c)

To determine: The situation in which a protein is a single polypeptide with a single ligand-binding site. As purified, the protein preparation is heterogenous, containing some protein molecules that are partially denatured and thus have a lower binding affinity for the ligand.

Introduction:

The cooperative binding of oxygen to the hemoglobin was first described by Archibald Hill in 1910. The cooperative binding of oxygen to Hb is a form of allosteric binding in which the binding of one ligand (oxygen) affects the binding affinities of other remaining binding sites of the receptor molecule. The measure of the degree of cooperativity is denoted by n_H, the Hill coefficient. If n_H is equal to 1, the binding of ligand is not cooperative, if n_H is greater than 1, the ligand binding indicates positive cooperativity, and if n_H is less than 1 the ligand binding indicates the negative cooperativity. The plotting of hill equations on a plot of log Y versus log L is called a Hill plot.