Elimination of basic gaps at high pH values in 2-DE

Area of Science:

• Proteomics
• Analytical Chemistry

Background:

• Two-dimensional (2-D) gel electrophoresis is a key proteomics technique.
• Gaps at the cathodic end of 2-D maps, particularly with wide-range immobilized pH gradient (IPG) strips (pH > 9), hinder protein analysis.
• The underlying cause of these gaps has been attributed to electro-osmotic water transport.

Purpose of the Study:

• To investigate the mechanism behind gap formation in 2-D maps.
• To identify methods for preventing gap appearance during isoelectric focusing (IEF).

Main Methods:

• Utilized wide-range IPG strips (pH > 9) for 2-D gel electrophoresis.
• Investigated the effect of electro-osmotic water transport on IPG strips.
• Analyzed the hydrolysis rate of polyacrylamide under different solution conditions.
• Tested electrode wick solutions containing varying concentrations of urea and thiourea.

Main Results:

• Gap formation is directly dependent on the electro-osmotic transport of water into the IPG strip.
• Replacing urea solution with water accelerates polyacrylamide hydrolysis, exacerbating gap formation.
• Employing 8 M urea or thiourea/urea solutions in the electrode wick effectively prevents gap formation.
• Overnight focusing is achievable without gaps using these optimized electrode wick solutions.

Conclusions:

• Electro-osmotic water influx and subsequent polyacrylamide hydrolysis are the primary causes of cathodic gaps in 2-D maps.
• Optimized electrode wick solutions (8 M urea or thiourea/urea) provide a robust method to eliminate gaps.
• This finding enables improved and uninterrupted overnight focusing for enhanced 2-D gel electrophoresis analysis.