Title: Learn: Introduction to Protein Gels
Course: BTEC-2020-301-302-303-F21 > Section: Protein Gels

Module2 Protein Gels

A stained SDS-PAGE gel. Image by Marta Ferreira. CC-By-SA.

Introduction

In this module, you will learn about electrophoresis of proteins. You have already applied the technique of electrophoresis to DNA: DNA is negatively charged, so when it is placed into an electrical field, the DNA moves toward the positive pole. Because the DNA is in an agarose gel, the larger a DNA fragment is, the slower it will move. The result is that agarose gel electrophoresis separates DNA fragments by size. DNA electrophoresis is relatively simple, because all DNA is negatively charged.

Proteins can also be separated by electrophoresis, but proteins may be positive, negative, or anywhere in between, depending on the amino acids that make up the protein. This makes electrophoresis of proteins more complicated than that of DNA.

Nondenaturing gel electrophoresis - electrophoresis of proteins that have not been subjected to denaturing (structure-destroying) treatments

In nondenaturing gel electrophoresis, the proteins’ native charge and structure are intact. You may never actually carry out nondenaturing gel electrophoresis, but in the following activity, I’d like you to consider how mass, shape and charge affect protein migration in a nondenaturing gel. This will help you understand SDS-PAGE which you will perform several times in this course.

Objectives

- Describe separation of proteins in a non-denaturing gel.
- Explain how SDS-PAGE separates primarily by mass.
- Explain the characteristics and function of the two layers involved in SDS-PAGE separation
- Pour gels.
- Run gels.
- Estimate mass of proteins using SDS-PAGE results.
- Determine the concentration of protein using a Bradford Assay