Enolase isozymes from Ricinus communis: partial purification and characterization of the isozymes.

The plastid and cytosolic isozymes of enolase from developing endosperm of castor oil seeds, Ricinus communis L. cv. Baker 296, were separated and partially purified. Each purified isozyme had a specific activity of approximately 200 mumol min-1 mg protein. The isozymes have similar pH optima for the forward reaction, but different optima for the reverse reaction. The divalent metal specificity is the same for both isozymes. In addition to differences in charge, the isozymes can be distinguished by their different kinetic constants, thermostability, and sensitivity to fluoride inhibition. Antibodies against yeast enolase isozyme I cross-react with Ricinus plastid enolase but not with the cytosolic isozyme.