Abstract
Photosystem II complexes are comprised of ~20 subunit proteins. Many of those subunit proteins are the hydrophobic membrane proteins; e.g., the grand average hydropathicity (GRAVY) of D1 and D2 proteins exceed 0.3. Similarly, other complexes in photosynthetic electron transport chain also consist of hydrophobic membrane proteins as well as small numbers of hydrophilic extrinsic subunit proteins. The expression level of these proteins under variable environment will be well investigated with two-dimensional gel-electrophoresis using iso-electric focusing for the first dimension (2D-gel). However, such kind of hydrophobic membrane proteins are not separated reliably on the conventional 2D-gel. We have developed a novel 2D-gel system to analyze hydrophobic proteins. For the iso-electric focusing, agarose was used as a supporting matrix and n-dodecyl-β-D-maltopyranoside was used as a surfactant. Using this system, all known subunit proteins in photosystem II complexes larger than ~10 kDa were reproducibly and clearly separated on the 2D-gel.
