Adaptive alterations in Lactobacillus casei: II. Variation in the levels of aldolase in cells grown on glucose and ribose

The growth of homofermentative Laclobacillus casei on ribose caused reduction in aldol cleavage of fructose-1,6-diphosphate (FDP) while enhancing activities for condensation of triose phosphates and of fructose-1,6-diphosphatase. The purified preparation of aldolase from L. casei was not inhibited by EDTA and was not affected by bivalent metal ions (Fe 2+ and Zn 2+). The inactivation of the enzyme by sodium borohydride only in presence of dihydroxyacetone phosphate (DHAP) suggested formation of a Schiff-base intermediate. The enzyme could be resolved into three active components on DEAE-cellulose chromatography. These fractions showed distinct differences in properties with respect to cleavage of FDP and condensation of triose phosphates. The fractions having high cleavage activity gave low condensation reaction. This component was also active for transaldolase reaction. The other two fractions gave higher rate of condensation and lower cleavage values. The profiles obtained for aldolase prepared from ribose-grown cells of L. casei indicated that there was drastic reduction in the component having high cleavage activity. The results suggest that the equilibrium of the reaction toward cleavage or condensation was determined by isoenzymic composition of aldolase which appears to be adaptively altered by metabolic regulatory controls operative in glucose or ribose-grown cells of L. casei.