A method for global analysis of complex proteomes using sample prefractionation by solution isoelectrofocusing prior...

Area of Science:

• Proteomics
• Biochemistry
• Analytical Chemistry

Background:

• Two-dimensional electrophoresis (2D PAGE) is vital for proteome research.
• Current 2D PAGE methods struggle to resolve complex eukaryotic proteomes (>10,000 proteins).
• High protein loads in 2D PAGE often lead to precipitation and aggregation.

Purpose of the Study:

• To develop and demonstrate a novel solution isoelectrofocusing device and method.
• To reproducibly prefractionate cell extracts for enhanced 2D PAGE.
• To improve the resolution, protein load capacity, and detection limits of proteome studies.

Main Methods:

• A prototype isoelectrofocusing device with separation chambers was used.
• Cell extracts were loaded into chambers with immobiline-containing polyacrylamide gels at specific pH values.
• Samples underwent isoelectric focusing for several hours, resulting in well-resolved fractions.

Main Results:

• Recoveries of fractionated proteins exceeded 80%.
• Nonideal behavior (precipitation/aggregation) was significantly reduced compared to direct 2D PAGE.
• The method allows for increased protein loads, resolution, and dynamic detection range.

Conclusions:

• The novel isoelectrofocusing method effectively prefractionates cell extracts for 2D PAGE.
• This approach enables quantitative comparisons of over 10,000 protein components.
• Estimated protein detection limits are as low as 1000 molecules per cell for mammalian proteomes.