Absolute protein quantification is an essential tool for system biology approaches and elucidation of stoichiometry of multi-protein complexes. In this chapter, a universal protocol for gel free absolute protein quantification in bacterial systems is described, which can be used for sample preparation prior to miscellaneous mass-spectrometry-based quantification workflows like AQUA, Hi3, and emPAI. In addition, a focus has been set to the specific challenges in antibiotic stress research.
Keywords: AQUA; Absolute protein quantification; Antibiotic stress response; Gel free proteomics; Hi3; In-solution digestion; QconCAT; Sample preparation; emPAI.