Difference Between 1D and 2D Gel Electrophoresis

The key difference between 1D and 2D gel electrophoresis is the properties used for the separation of proteins on gel electrophoresis. 1D gel electrophoresis only separates proteins based on the molecular weight while 2D gel electrophoresis separates proteins based on its iso-electric point and molecular weight.

Protein separation by gel electrophoresis is an important technique to characterize proteins. Proteins have varying properties; therefore, separation is more complex in comparison to DNA separation by Agarose gel electrophoresis.

CONTENTS

1. Overview and Key Difference
2. What is 1D Gel Electrophoresis
3. What is 2D Gel Electrophoresis
4. Similarities Between 1D and 2D Gel Electrophoresis
5. Side by Side Comparison – 1D vs 2D Gel Electrophoresis in Tabular Form
6. Summary

What is 1D Gel Electrophoresis?

1D Gel Electrophoresis, also known as one dimension gel electrophoresis, is a method of protein separation based on the molecular weight. Protein separation mainly takes place using polyacrylamide gel electrophoresis. Based on the concept of gel electrophoresis, molecules separate on their property of molecular weight and charge.

Therefore, to give a uniform charge to the proteins, Sodium dodecyl sulfate (SDS) treatment is done prior to the gel electrophoresis. SDS denatures proteins and provides a uniform negative charge on the protein; when the application of the electric field takes place, the proteins migrate to the positive terminal based on their molecular weight. Thus, in separation, only one property is considered. This is why this method is termed as 1D gel electrophoresis.

During 1D gel electrophoresis, proteins are separated based on their molecular weight. In this regard, the lower weight molecules migrate faster in the gel compared to the high molecular weight proteins. Thus, high weight proteins remain close to the wells.

What is 2D Gel Electrophoresis?

2D gel electrophoresis or two-dimensional gel electrophoresis separates proteins based on two properties. The two properties are the iso-electric point of the protein and molecular weight. This method of protein separation increases the resolution of protein separation. The iso-electric point of the protein depends on the pH at which the protein is neutral.

Thus, in 2D gel electrophoresis, the protein is allowed to run on a fixed pH gradient in the first dimension. In the second dimension, the proteins are separated using vertical or horizontal polyacrylamide gel electrophoresis. Thus, the proteins separate according to their molecular weight in the second dimension.

Besides, this method of gel electrophoresis increases the resolution of protein separation. Therefore, the separated proteins are purer. However, the cost of the technique is much higher than one dimension gel electrophoresis.

What are the Similarities Between 1D and 2D Gel Electrophoresis?

• Both techniques separate proteins.
• Hence, they are important in characterizing proteins.

What is the Difference Between 1D and 2D Gel Electrophoresis?

The key difference between 1D and 2D gel electrophoresis is that 1D gel electrophoresis separates proteins based only on the molecular weight while 2D gel electrophoresis separates proteins based on both iso-electric point and molecular weight. Due to this basic difference between 1D and 2D gel electrophoresis, the resolution of separation of the proteins and the cost of the two techniques also vary. 2D gel electrophoresis shows high resolution than 1D gel electrophoresis. However, 2D gel electrophoresis is more costly than 1D gel electrophoresis.

Below infographic summarizes the difference between 1D and 2D gel electrophoresis.

Summary – 1D vs 2D Gel Electrophoresis

Separation of proteins relies on many factors. 1D gel electrophoresis separates proteins based only on the molecular weight. However, two dimensional or 2D gel electrophoresis increases the resolution of the protein separation. Further, 2D gel electrophoresis separates proteins based on the iso-electric point and the molecular weight. Therefore, these data are important for downstream processing of proteins and in the field of proteomics. Thus, this is the summary of the difference between 1D and 2D gel electrophoresis.

Reference:

1. Galeva, Nadezhda, and MichailAltermann. “Comparison of One-Dimensional and Two-Dimensional Gel Electrophoresis as a Separation Tool for Proteomic Analysis of Rat Liver Microsomes: Cytochromes P450 and Other Membrane Proteins.” Proteomics, U.S. National Library of Medicine, June 2002, Available here.

Image Courtesy:

1. “Electrophoresis – Filling 1D gel wells with proteins mixture” By Jean-Etienne Poirrier – Filling 1D gel wells with proteins mixture (CC BY-SA 2.0) via Commons Wikimedia
2. “2D electrophoresis” By National Institute of Health – Center for Cancer Research Nanobiology Program, National Institute of Health (Public Domain) via Commons Wikimedia