Hi, I am running a size exclusion chromatography experiment with a buffer containing Potassium Acetate as a salt. I analyse these fractions through SDS-PAGE. After boiling my SEC fractions in laemmli buffer and leaving to cool to RT I notice a loose precipitate in the tube. After spinning this down and loading the supernatant on an SDS-PAGE gel I can visualize my proteins of interest.
I was wondering if anyone could help me understand what this precitipiate is? I believe it could be potassium dodecyl sulphate? Is it expected that this would also precipitate some of my protein and reduce my soluble yield that I can visualize by SDS-PAGE?
Thank you.
You are right. Potassium dodecyl sulfate is much less soluble than sodium dodecyl sulfate.
potassium DS 0.415 mg/ml.
sodium DS 200 mg/ml
Liam Pollock , That's all Dr. Shapiro said. In addition, if the SDS concentration in the SDS-PAGE sample buffer is 1%, it is equivalent to 35 mM. In my experience, low concentrations of potassium salts, around 10-20 mM, did not have effect. Because there were no apparent precipitation in the end. However, in the presence of a potassium salt of about 50 mM, potassium DS increased and precipitated. I was worried to insufficient denature, I changed buffer salts to sodium.
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