Abstract
A manganese protein was solubilized from the thylakoids of the cyanobacterium Plectonema boryanum with a cholate-deoxycholate mixture, and purified to homogeneity by gel-filtration. Isolated manganese protein had a molecular weight of 13,000 and showed catalase activity, which was insensitive to 3-aminotriazole. The antibody raised against the manganese protein inhibited the oxygen evolution using dichlorophenol indophenol (DCIP) as the electron acceptor by P. boryanum thylakoids, but not the diphenylcarbazide-supported photoreduction of DCIP and ascorbate-supported photoreduction of methyl viologen in the presence of DCMU. These observations suggest that isolated manganese protein is a component of the oxygen evolving enzyme, water dehydrogenase.