Protein extraction from Saccharomyces cerevisiae at different growth phases.

Saccharomyces cerevisiae is an established model organism with a well characterized genome. However, this model presents a unique problem due to a very resistant cell wall which develops in the late stationary phase resulting in sub-optimal extraction of proteins from such cells using majority of the cell lysis protocols. In this study, several methods from the literature with modifications thereof for lysis of S. cerevisiae cells were analyzed for their suitability for redox proteomics and biological activity studies of both exponential and late stationary phase cultures. The protocols applied are glass bead lysis, sonication, their combinations, alkali extraction, hot-SDS extraction methods and their modifications. The glass bead lysis method showed low yield but could be convenient in cases where in vitro processing steps post extraction is required or if only hydrophilic proteins are of interest. Hot-SDS and alkali extraction protocols yielded higher amount of proteins and these methods are potentially suitable for Western blotting and redox proteomic studies but allow no post-processing treatment(s) on the extracts which may be required for aging- and oxidative stress-related or other studies.