After depletion of abundant proteins from my sample, I still see albumin and other abundant proteins after LC-MS analysis. Did the depletion work?
Depletion does not remove all abundant proteins from the sample. Even with 99% depletion of a specific plasma protein, highly abundant proteins will still be the most abundant proteins in the sample detected by MS analysis. However, depletion significantly decreases the most abundant plasma proteins enabling identification of lower abundant proteins.
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How do I proceed to downstream mass spec sample preparation after abundant plasma protein depletion?
After the depletion, samples are significantly diluted in buffer. Depleted samples should be concentrated by speed vac drying, solvent precipitation, or diafiltration. Samples dried using a speedvac are directly compatible with the EasyPep kit chemistry after resuspension using the Lysis Solution.
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What is the maximum loading capacity for the High Select Depletion columns?
Mini columns can deplete up to 10 µL (600 µg) of plasma or serum; midi columns can deplete up to 100 µL (6000 µg) of plasma or serum.
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What is the percentage of albumin that is removed using abundant protein depletion columns?
More than 99% of albumin can be depleted when columns use the recommended sample to resin ratio.
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How do I assess efficiency and reproducibility of abundant protein depletion in plasma samples?
ELISA and mass spectrometry analysis are often used for evaluation of depletion performance. Protein yields after depletion can be measured using the BCA assay.
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