Characterization and purification of a hydrogenase from the eukaryotic green alga Scenedesmus obliquus

Several catalytic properties of the hydrogenase from Scenedesmus obliquus have been examined to optimize the purification conditions. The Km-value for H2-evolution in the presence of the most effective electron mediator methylviologen is 0.66 mM. The pH-optimum is 6.3, the temperature-optimum is 50 degrees C and the energy of activation is 38.4 +/- 2 kJ.mol-1. The soluble hydrogenase from the green alga, Scenedesmus obliquus, was purified 1290-fold to homogeneity. The enzyme consists of two subunits with molecular masses of 55 kDa and 36 kDa. The molecular weight of the native enzyme, determined by gel filtration, is 150 +/- 5 kDa.