Fructose 1,6-diphosphate aldolase of Candida utilis: purification and properties

Fructose diphosphate aldolase has been purified from Candida utilis. The final product is homogeneous by several criteria and stable for several weeks in the presence of a reducing agent. The molecular weight from equilibrium sedimentation measurement is 67,500. The enzyme contains 1 mole of zinc per mole of enzyme and is activated by K⁺ ions; in these properties it resembles the enzyme from Saccharomyces cerevisiae. It is strongly inhibited by chelating agents such as EDTA, o-phenanthroline, and pyrophosphate. The enzyme catalyzes the cleavage of sedoheptulose 1,7-diphosphate and fructose 1-phosphate; the reaction rates with these substrates are 2.5 and 0.08% of that with fructose 1,6-diphosphate, respectively. No evidence was obtained for the formation of a Schiff base intermediate with the Candida enzyme. Since transaldolase from C. utilis does form a Schiff base intermediate, this organism represents a case in which both types of enzyme are present.