Immunological Characterization of the Pyrophosphate Dependent Fructose-6-Phosphate Phosphotransferase

The pyrophosphate dependent phosphofructokinase (PFP, EC 2.7.1.90) was purified from potato tubers, bean seeds and cucumber seeds. The PFP of all three species appears to contain two subunits with a molecular weight of approximately 60,000 and 66,000 dalton. The purified proteins were used as the antigens to produce polyclonal antibodies in rabbits. Two of the obtained sera (anti-potato PFP and anti-cucumber PFP) proved to be monospecific for the PFP polypeptides on protein blots. The antipotato serum cross reacts with the PFP from all the tested higher plant species on protein blots, but no cross reaction with the PFP of Propionibacterium sharmanii was found. This shows that the PFP subunits from the higher plant species have similar antigenic determinants in the primary structure but differes largely from that of the Propionibacterium. The differences observed in the efficiency of the sera to inactivate the PFP from the different species, however, indicate that the surface antigenic determinants on the native PFP enzymes differ between the higher plant species and even within the Cucurbitaceae.