Introduction
Reproducible quantitative proteomics necessitates complete and efficient sample digestion. No amount of improvements in the hardware or software for data acquisition and analysis will compensate for poor sample preparation and incomplete digestion. To improve sample digestion, various approaches such as combinations of multiple proteases, elevated enzyme concentration(s), or addition of detergents or other denaturants, have been used with varying degrees of success. Pressure cycling, in which the reaction is exposed to cycles of high hydrostatic pressure, has been shown to accelerate digestion with proteases. Here we present a systematic comparison between samples digested with and without pressure. We emphasize reduced time, improved quantitation and sequence coverage. In addition we examine the specificity and activity of several enzymes under PCT conditions.