Chapter 5, Problem 7E

(a)

Summary Introduction

To explain: The order of amino acids Arg, His, and Leu that eluted from carboxymethyl column at pH 6.

Concept introduction: Separation and purification of biological macromolecules are done using carboxymethyl columns. These columns have carboxymethyl functional groups –CH₂OCH₂COOH. At neutral pH, the carboxymethyl group is ionized and becomes negatively charged. Hence, it is a weak cation exchanger.

(b)

Summary Introduction

To explain: The order of amino acids Glu, Lys, and Val that are eluted from diethylaminoethyl column at pH 8.

Concept introduction: DEAE (Diethylaminoethyl) cellulose chromatography is an ion exchange chromatography used for the separation and purification of proteins. DEAE cellulose is a weak anion exchanger, so the negatively charged protein binds to DEAE. It separates the substance based on their charges, where a negatively charged protein binds with the positively charged DEAE.