A single subunit P‐700 reaction center of the thermophilic cyanobacteriumMastigocladus laminosus

Abstract
The isolation and characterization of a single subunit Photosystem I reaction center of the thermophilic cyanobacteriumMastigocladus laminosusis described. The subunit isolated in 0.1% SDS is fully active in P‐700 bleaching and oxidizes cytochromecin the light. Depending on denaturing conditions, the protein appears on SDS—PAGE in the 70 kDa or 50 kDa region and contains bound chlorophyll in both forms. The 70 kDa form shows all the activities of an intact reaction center.