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Sample-streaks and smears in immobilized pH gradient gels
J Esteve-Romero1, E Simò-Alfonso, A Bossi
1Universitat Jaume I, Departament de Ciencies Experimentals, Area de Quimica Analitica, Castellò, Spain.
Electrophoresis
|April 1, 1996
Summary
Reducing pK 7.0 acrylamido buffer levels in immobilized pH gradient (IPG) gels prevents protein streaks and smears. Lowering this buffering ion concentration is key for clearer 2D gel electrophoresis results.
Area of Science:
- Proteomics
- Biochemistry
- Analytical Chemistry
Background:
- Immobilized pH gradient (IPG) electrophoresis is a critical technique for protein separation.
- Protein streaking and smearing on IPG gels can significantly hinder analysis and interpretation.
- The role of specific buffering components in gel performance requires detailed investigation.
Purpose of the Study:
- To investigate the impact of the pK 7.0 acrylamido buffer on protein migration patterns in IPG gels.
- To determine the optimal concentration of the pK 7.0 buffer for minimizing artifacts like streaks and smears.
- To explore potential causes for the observed artifacts, including buffer hydrophobicity and oligomerization.
Main Methods:
- Utilizing IPG gel formulations with varying concentrations of pK 7.0 acrylamido buffer (0 mM, 3 mM, and 10 mM).
- Analyzing protein separation patterns for both hydrophobic and hydrophilic proteins across different gel conditions.
- Assessing protein migration using standard protein markers and recombinant enzymes.
- Evaluating the hydrophobicity of the pK 7.0 buffer via water/n-octanol partitioning.
- Examining commercial buffer preparations for potential oligomers.
Main Results:
- Protein smears and streaks were directly proportional to the total amount of pK 7.0 acrylamido buffer present.
- Severe smears occurred at 10 mM pK 7.0 buffer, affecting both hydrophobic and hydrophilic proteins.
- Artifacts were largely eliminated when the pK 7.0 buffer was absent or limited to 3 mM.
- The pK 7.0 buffer exhibited moderate hydrophobicity (P = 0.5), and oligomers in commercial preparations were suspected contributors to smears.
Conclusions:
- The concentration of pK 7.0 acrylamido buffer is a critical factor influencing the quality of protein separation in IPG gels.
- Reducing pK 7.0 buffer levels below 3 mM effectively abolishes protein streaks and smears.
- Oligomeric forms of the pK 7.0 buffer, potentially arising during synthesis, may contribute to observed artifacts, necessitating quality control of buffer preparations.