Photosynthetic properties of extracts of Anacystis nidulans prepared by lysozyme digestion

Abstract

Cell-free extracts of A. nidulans show high rates of cyclic and noncyclic photophosphorylation and P/2e ratios of about 0.8. These extracts also reduced ferricyanide at rates as high as 700 μmol/mg chlorophyll per hour. Rates of dichlorophenol indophenol (DCPIP) reduction and reduced cytochrome c oxidation similar to those previously reported in the literature have also been observed. The extracts, however, showed no NADP-reducing capacity. Subjecting cell-free extracts to cold shock caused no decline in electron flow but a marked decline in photophosphorylation. The sensitivity of photosynthesis of this organism to cold shock (1, 2) might be explained, at least to some extent, by this decline in photophosphorylation.