Abstract
Recently, we purified photoystem II (PSII) particles from a marine centric diatom, Chaetoceros gracilis, after disruption of the cells by freeze-thawing [Nagao et al. (2007) Biochim. Biophys. Acta 1767: 1353-1362.]. However, freeze-thawing readily disrupted centric diatom cells but not pennate diatom cells. In this study, we found that the cells of a marine pennate diatom, Phaeodactylum tricornutum, were disrupted with an artist's airbrush, and then we prepared thylakoid membranes retaining oxygen–evolving activity. We also succeeded in purification of PSII particles by differential centrifugation and subsequent sucrose density-gradient centrifugation of the detergent solubilized thylakoid membranes. The diatom PSII particles contained the extrinsic Psb31 protein found in the C. gracilis PSII particles, and showed the high oxygen-evolving activity. Further analysis is undergoing to identify all of the P. tricornutum PSII protein components.
