Intracellular Location and Possible Function of Malic Dehydrogenase Isozymes from Young Maize Root Tissue

Abstract
Three electrophoretic NAD malic dehydrogenase isozymes were separated from young maize root tips. Two distinct bands were associated with the mitochondrial preparations and one from the supernatant. The latter seemed to be contaminated with the mitochondrial bands. The hypothesis was presented that the soluble or cytoplasmic malic dehydrogenase functions in non-autotrophic CO2 metabolism and the mitochondrial in tricarboxylic acid cycle activity.