Die Stöchiometrie der Photosynthese in isolierten Chloroplasten

Abstract

The stoichiometry of photosynthesis has been estimated with spinach chloroplasts isolated under conditions in which the loss of protein during the washing procedure can be avoided. The TPN-reduction is definitely higher as described in literature. Without further addition of exogenous enzyme or extract the chloroplasts from primary leaves reduce 100 —200 µmoles TPN/mg chlorophyll and hour. In air the TPNH-value is 20—30% lower as in nitrogen. However, compared to the high TPNH-concentration the ATP-level is too low. The ATP-concentration increases by addition of ascorbate whereas this has no influence on the TPN-reduction. Without further addition of ascorbate the stochiometry TPNH : ATP : O is 2:1:2. The low ATP-value is only partly due to an ATPase. The difference cannot be explained by the presence of this enzyme. Even in presence of ascorbate and with the calculation of the activity of the ATPase we never estimated the theoretically required value.