High specific activity ribulose 1,5-bisphosphate carboxylase-oxygenase from Nicotiana tabacum.

Ribulose 1,5-bisphosphate carboxylase (EC.4.1.1.39) has been obtained from Nicotiana tabacum leaf homogenates with specific activites from 0.5 to 0.8 µmol CO2 fixed (mg protein min)(-1). These activities are reconciled with much lower, previously reported activities. The results suggest that if the tobacco enzyme is assayed under optimum conditions there is little difference in the intrinsic specific activities of tobacco and spinach ribulose 1,5-bisphosphate carboxylase. Several factors affecting activity measurements were examined.