Removal of sodium dodecyl sulfate from protein samples

Abstract

Sodium dodecyl sulfate (SDS) is a widely used detergent for protein denaturation and solubilization. However, application of SDS in the sample preparation for the liquid chromatographic-mass spectrometric analysis is limited because commonly used SDS concentrations interfere with reversed phase liquid chromatography and electrospray ionization mass spectrometry. In order to analyse SDS pretreated proteins by the above-mentioned methods SDS must be completely removed or its concentration must be lowered to less than 0.01%. In this work we present a comparison of different SDS removal strategies based on SDS ultrafiltration, protein precipitation and SDS precipitation methods. Every strategy was optimized so that the initial 4% SDS concentration was lowered to less than 0.01% and the initial sample volume remained unchanged. The modified Mukerjee’s photometric method was used for the SDS quantitation in the presence of model protein bovine serum albumin and the recovery of model protein was evaluated using reversed phase ultra performance liquid chromatography. The main advantages and drawbacks of every strategy are discussed.