Chloroplast class I and class II aldolases are bifunctional for fructose-1,6-biphosphate and sedoheptulose-1,7-biphosphate cleavage in the Calvin cycle

Class I and class LI aldolases are products of two evolutionary non-related gene families. The cytosol and chloroplast enzymes of higher plants are of the class I type, the latter being bifunctional for fructose-1,6- and sedo heptulose-l,7-P-2 in the Calvin cycle. Recently, class II aldolases were de tected for the cytosol and chloroplasts of the lower alga Cyanophora parado xa. The respective chloroplast enzyme has been shown here to be also bifunc tional for fructose-1,6- and sedoheptulose-1,7-P-2. Kinetics, also includin g fructose-1-P, were determined for all these enzymes. Apparently, aldolase s are multifunctional enzymes, irrespective of their class I or class II ty pe. (C) 1999 Federation of European Biochemical Societies.