Chapter 3, Problem 11P

(a)

Summary Introduction

To determine: The net charge of the given molecule at $\text{pH}$ 3, 8, and 11.

Introduction: pH is used to specify the acidity and basicity of the solution. When $\text{pH}$ is greater than ${\text{pK}}_{\text{a}}$, then ionizing groups lose the protons $\left({\text{H}}^{\text{+}}\right)$.

Given: The given peptide molecule has the sequence as follows: Glu-His-Trp-Ser-Gly-Leu-Arg-Pro-Gly.

(b)

Summary Introduction

To estimate: The pI of the given peptide.

Introduction: Isoelectric point $\left(\text{pI}\right)$ is the pH at which the net charge of a molecule becomes zero or the molecule becomes electrically neutral.