Tris interference in IEF and 2-DE

Area of Science:

• Biochemistry and Biophysics
• Electrophoresis Techniques
• Proteomics

Background:

• Dried Immobilized pH Gradients (IPGs) are rehydrated with protein solutions for isoelectric focusing (IEF).
• Ionic constituents and protein concentrations are initially uniform across the IPG strip.

Purpose of the Study:

• To investigate the focusing behavior of Tris buffer during IEF in hydrated IPGs.
• To understand the impact of Tris accumulation on voltage distribution and protein migration patterns.

Main Methods:

• Isoelectric focusing (IEF) on rehydrated Immobilized pH Gradients (IPGs).
• Observation of Tris buffer focusing and its interaction with protein migration.
• Analysis of conductivity and voltage gradients within the IPG strip.

Main Results:

• Tris, initially at low concentration, focuses at its pKa, forming a localized zone of high conductivity.
• This Tris-rich zone causes a sharp voltage drop, influencing the migration of nearby proteins.
• Basic proteins align at the periphery of the Tris zone, while acidic proteins may be impeded.

Conclusions:

• Tris buffer's focusing behavior in IPGs significantly impacts electrophoretic conditions.
• The localized voltage drop can alter protein separation, particularly for basic and acidic proteins.
• Understanding Tris focusing is crucial for optimizing IEF protocols and interpreting results.