Rifampicin ≥90 %, for biochemistry Rifampicin inhibits bacterial DNA-dependent RNA-polymerase and consequently prevents transcription. Its spectrum of activity is strictly bacterial (the eukaryotic DNA-dependent RNA-polymerase can only be inhibited at extremely high concentrations) and rifampicin is particularly very effective against mycobacteria. Enterbacteria, acinetobacteria and pseudomonades are resistant against rifampicin. The resistance-mediating genes can be applied as selection markers in molecular biology. Light-sensitive. Store in the dark!Stock solution: 100 mg/ml in chloroform or DMSO, 15 mg/ml in methanol, 1 mg/ml in water (pH 7,3)Store stock solution at -20 °C, is stable for approx. 2 weeks in DMSO when stored in the dark at 4 °CWorking concentration: 20-200 µg/ml