Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 microM EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 microM NiCl2 photohydrogen evolution was increased by 20-40%. Addition of EDTA up to a final concentration of 1.5 mM had no effect on the activity of hydrogenase in cell-free hydrogenase preparations. Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.

Anaerobiosis↗

PubMedDate not supplied

Purification and characterization of cytochrome c6 from the unicellular green alga Scenedesmus obliquus.

Purification of a soluble cytochrome c6 from the unicellular green alga Scenedesmus obliquus by a simple and rapid method is described. The purification procedure includes ammonium sulfate precipitation and non-denaturating PAGE. The N-terminal sequence of the first 20 amino acids was determined and shows 85% similarity and 75% identity to the sequence of cytochrome c6 from the green alga Monoraphidium braunii. The ferrocytochrome shows typical UV/VIS absorption peaks at 552.9, 521.9 and 415.7 nm. The apparent molecular mass was estimated to be 12 kDa by SDS-PAGE. EPR-spectroscopy at 20 K shows resonances indicative for two distinct low-spin heme forms.

Amino Acid Sequence↗