This project supports continued studies with three enzymes closely related to the malate branching point of metabolism, the NAD malic enzyme, phosphoenolpyruvate carboxylase and malate dehydrogenase. The studies planned include several distinct research efforts with each enzyme. These include among others, the means by which MDH is regulated; the role of diurnal changes in leaf composition in controlling Crassula malic enzyme; study of the kinetics of aggregation of all three enzymes and identification of the amino acids composing the active and regulatory sites of PEPC. This project has for several years been devoted to the study of the metabolic reactions around malate in an effort to help with the understanding of how these critical metabolic steps relate to the ability of plants to adapt to permanently stressed conditions (e.g. CAM), survive transient stresses (e.g. low temperatures or low nutrients), carry out functions requiring temporary provision of high levels of energy or anaplerotic activity such as fruit development, or to make special adjustments providing high competitiveness such as C4 metabolism.***//
