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

The main difference between 1D and 2D gel electrophoresis is that 1D gel electrophoresis separates proteins according to molecular weight, whereas 2D gel electrophoresis separates proteins according to isoelectric point and molecular weight.

1D and 2D gel electrophoresis are two types of gel electrophoresis that separate proteins. Gel electrophoresis is a technique used to separate DNA, RNA, and proteins depending on their size and charge.  

Key Areas Covered

1. What is 1D Gel Electrophoresis
     – Definition, Features, Importance
2. What is 2D Gel Electrophoresis
     – Definition, Features, Importance
3. Similarities – 1D and 2D Gel Electrophoresis
     – Outline of Common Features
4. Difference Between 1D and 2D Gel Electrophoresis
     – Comparison of Key Differences

Key Terms

1D Gel Electrophoresis, 2D Gel Electrophoresis

What is 1D Gel Electrophoresis

1D gel electrophoresis is a technique to separate proteins according to their molecular weight. The sizes of proteins need to be 10 to 300 kDa in size. In this process, SDS is used to isolate proteins by denaturing them. SDS is a detergent; the tertiary structure of proteins is disrupted by it, bringing the folded protein down into a linear molecule. It coats that linear protein molecule with a uniform negative charge. Moreover, 1D gel electrophoresis consists of two gels with different concentrations. The top layer is called the stacking gel, to which the samples are loaded, while the bottom layer is called the resolving gel. The polyacrylamide concentration of stacking gel is 3.5-4% (large pore size), and it concentrates proteins in one band. The polyacrylamide concentration in the resolving gel is 4-20% (small pore size), and it separates proteins based on their size.

Figure 1: 1D Gel Electrophoresis

Furthermore, with the application of the electric field, negatively charged proteins move toward the positive electrode through the acrylamide matrix. Large proteins move slowly through the acrylamide, while small proteins move quickly through the acrylamide. Therefore, proteins separate according to their molecular weight in 1D gel electrophoresis.

What is 2D Gel Electrophoresis

2D gel electrophoresis is a primary technique in proteomics to separate protein molecules according to their isoelectric points and molecular weight. In the first dimension, proteins separate according to their isoelectric points. In the second dimension, proteins separate according to their molecular weight. On the other hand, 2D gel electrophoresis uses combinations of methods 2D gel, IEF, and SDS-PAGE to analyze complex mixtures of proteins. Similar to 1D gel electrophoresis, proteins are negatively charged in 2D gel electrophoresis with SDS treatment.

Figure 2: 2D Gel Electrophoresis

Moreover, the gel with IEF is horizontally inserted into the SDS-PAGE. Therefore, the proteins separated by isoelectric points in IEF are further separated by their molecular weight. More than 1000 proteins can be separated in this method in 20×20 cm large gels. For visualization, Coomassie dye is used when the protein amount is 10 ng, and silver or fluorescent dyes are used when the amount of proteins is around 0.5 ng.

Similarities Between 1D and 2D Gel Electrophoresis

• 1D and 2D gel electrophoresis are two types of gel electrophoresis used to separate proteins.
• Gel electrophoresis is a technique to separate DNA, RNA, and proteins according to their size and charge.

Difference Between 1D and 2D Gel Electrophoresis

Definition

1D gel electrophoresis refers to a method that separates protein by molecular weight over a range of about 10 to 300 kilodaltons (kDa), while 2D gel electrophoresis refers to a primary technique of proteomics separating the complex mixture of samples using two different properties of the proteins.

Type of Separation

1D gel electrophoresis separates proteins according to their molecular weight, while 2D gel electrophoresis separates proteins according to their isoelectric point and molecular weight.   

Resolution

While 1D gel electrophoresis has a low resolution, 2D gel electrophoresis has a high resolution.

Cost

1D gel electrophoresis is less costly, while 2D gel electrophoresis is highly costly.

Conclusion

In brief, 1D gel electrophoresis and 2D gel electrophoresis are two types of gel electrophoresis that separate proteins according to their size and charge. 1D gel electrophoresis separates proteins according to their molecular weight. Therefore, it has a low resolution, and it is a less costly experiment. In comparison, 2D gel electrophoresis separates proteins according to their isoelectric point and molecular weight. 2D gel electrophoresis has a high resolution, and it is a highly costly experiment. Hence, the main difference between 1D and 2D gel electrophoresis is their type of separation.

References:       

1. “How does 1D gel electrophoresis work? “-. Kendrick Laboratories.
2. “Two-dimensional gel electrophoresis.” ScienceDirect Topics. 

Image Courtesy:

1. “Electrophoresis – Filling 1D gel wells with proteins mixture” By Jean-Etienne Poirrier – Own work (CC-BY SA 2.0) via Commons Wikimedia
2. “2D-Gel” By Caspardavid at German Wikipedia – Own Work (CC-BY SA 3.0) via Commons Wikimedia