PURIFICATION METHODS FOR RECOMBINANT LACTOBACILLUS-CASEI THYMIDYLATE SYNTHASE AND MUTANTS - A GENERAL, AUTOMATED PROCEDURE

General procedures for the rapid, large-scale purification of recombinantLactobacillus casei thymidylate synthase and its mutants have been established. An effective method employs sequential phosphocellulose and hydroxylapatite chromatography. Crude cell extracts are directly applied to phosphocellulose, and the enzyme is obtained in a nearly pure state by stepwise elution with KCI. The eluate is directly applied to hydroxylapatite, and the homogeneous enzyme is eluted with a gradient of potassium phosphate. The method has been successful for the purification of recombinant wild-type enzyme and all mutants thus far examined. The entire purification procedure has been automated using a commonly available FPLC system and can be performed in several hours with minimal operator time. © 1992 Academic Press, Inc.