Analysis of dilute protein samples is a challenging task for scientific and industrial labs all over the world. Although there are different methods available that allow for protein enrichment from various biological sources, all of them have serious limitations apart from their advantages. In order to perform highly reproducible and sensitive protein analysis of lowest concentrated samples, we optimized a method to enrich proteins on affinity beads (StrataClean) recently. This chapter describes the general protocol of this strategy, thereby discussing the power as well as the limits of this technique for qualitative and quantitative proteomic studies. Moreover, additional application and protocol variants will be discussed, expanding the number of compatible up- and downstream processing techniques compared to the originally published method. Hence, we evaluated the reduction of time for sample preparation by use of preprimed affinity beads and shorter incubation durations as well as the influence of high concentration of salts or urea in the sample buffer.
Keywords: Protein enrichment; Sample cleanup; Sample preparation; Solid-phase extraction; StrataClean.
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