Crystalline L-Ribulose 5-Phosphate 4-Epimerase from Escherichia coli

Abstract l-Ribulose 5-phosphate 4-epimerase has been crystallized from l-arabinose-induced cells of Escherichia coli B/r strain F' araB-24/araB-24 after a 40-fold purification. The enzyme is homogeneous in the ultracentrifuge and 98% pure by acrylamide gel disc electrophoresis. The molecular weight determined by sedimentation equilibrium is 1.03 ± 0.01 x 105. The enzyme is free of d-ribulose 5-phosphate 3-epimerase activity, does not exhibit any cofactor requirement, and shows maximal activity from pH 7 to 10. An amino acid analysis is presented.