The effect of SO 3 (--) on the activity of ribulose-1,5-diphosphate carboxylase in isolated spinach chloroplasts.
SO 3 (--) inhibits the activity of ribulose-1,5-diphosphate carboxylase in isolated spinach chloroplasts. It shows a non-competitive inhibition pattern with respect to ribulose-1,5-diphosphate and Mg(++) but a competitive one with respect to HCO 3 (-) . The K i -values are 14 mM SO 3 (--) and 9.5 mM SO 3 (-) respectively for the non-competitive inhibition but only 3.0 mM SO 3 (--) in the case of competitive inhibition with HCO 3 (--) as a substrate. Thus it is concluded that the competitive inhibition type will predominate at low SO 3 (--) and low internal CO2 concentrations.
Botanisches Institut der Technischen Universität München, Munchen, Germany.
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Ziegler