Isolating intact chloroplasts from small Arabidopsis samples for proteomic studies.

We have established a method for the isolation of chloroplasts from Arabidopsis thaliana that allows proteomic studies in the context of biotic stress with small amounts of starting material. Employing a 50% Percoll layer to separate crude filtrates, the required leaf material was reduced to 2-3g, yielding more than 300 microg of chloroplast proteins. The quality of this fraction was confirmed by immunological, enzymatic, and gel-based assays.