L-RHAMNULOSE 1-PHOSPHATE ALDOLASE FROM ESCHERICHIA COLI CRYSTALLIZATION AND PROPERTIES

L-Rhamnulose 1-phosphate aldolase has been purified and crystallized from L-rhamnose-induced cultures of Escherichia coli as well as from a strain of the organism constitutive for L-rhamnose utilization. The enzyme is homogeneous by acrylamide gel disc electrophoresis, by electrophoresis on cellulose acetate, and by immunoelectrophoresis and immunodiffusion in agar gel. It is also homogeneous by sedimentation velocity and density gradient centrifugation. Molecular weight determined by density gradient centrifugation and by Sephadex gel thin-layer chromatography is in the order of 1.3-1.4 × 105daltons. Na+, Cs+, NH4+, Rb+, or K+is required for activity; K% for KC1 is 6 mM. The enzyme has a sharp pH optimum of 7.5. Kmis 0.3 mM for L-rhamnulose 1-phosphate, 6.0 mM for L-lactaldehyde, and 3.0 mM for dihydroxyacetone phosphate. Kequilfor the reaction L-rhamnulose 1-phosphate ⇋ L-lactaldehyde + dihydroxyacetone phosphate is 8.3 × 10-5m. The enzyme is specific for ketose 1-phosphates which have the configuration D at C-3 and L at C-4 in the Fischer projection formula. © 1969, American Chemical Society. All rights reserved.