Malate Dehydrogenase Isoenzymes in Cotton Leaves of Different Ages

Abstract Malate dehydrogenase isoenzymes from the blades of different aged leaves of the cotton plant have been investigated. The total extractable malate dehydrogenase activity varied widely between leaves of different ages and different locations on the plant. Malate dehydrogenase zymograms developed from the extracts which contained significantly different levels of enzyme activity appear to indicate the presence of different groups of malate dehydrogenase isoenzymes in leaves of different ages. However, under appropriate conditions of polyacrylamide gel electrophoresis, the same number of malate dehydrogenase isoenzymes with the same relative mobilities were detected in all the leaves studied. These findings are discussed in relation to reports that malate dehydrogenase isoenzymes change with plant development or that they have different roles in the plant.