A screening procedure for the solubilization of chloroplast membrane proteins from the marine green macroalga Ulva lactuca using RP–HPLC–MALDI-MS

A protocol for purification and analysis of chloroplast membrane proteins in the green macroalga Ulva lactuca has been developed, including reversed phase high performance liquid chromatography (RP–HPLC) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Five different solvents were evaluated for extraction of membrane proteins by three methods. The highest protein yield was achieved when proteins were extracted directly from the chloroplasts using the solvent hexafluoroisopropanol. A range of proteins of increasing hydrophobicity was separated by HPLC. Analysis of both HPLC fractions and non-separated samples by MALDI-TOF-MS revealed proteins with molecular weights spanning between 1 and 376 kDa.