Strategies to evade false positives in the in situ analysis of peptide antibiotics in SDS-PAGE gels.

In situ activity assay is one of the promising techniques for the characterization of peptide antibiotics. This assay was carried out for the peptide purified from a new bacterial isolate Paenibacillus alvei and commercial peptide antibiotic polymixin E. Towards this, the routine and new protocols were tried. Interestingly, the unexpected result of these experiments - the "switch over activity" has led us to have further investigations. Here, we have addressed the potential problem in the methodology of in situ assay and demonstrated a fool proof protocol to evade the false positive results.