This proposal deals with biophysical studies of structure-function relationships in two allosteric enzymes--fructosebisphosphatase and aspartokinase-homoserine dehydrogenase. A 300 Mhz high resolution fourier transfor NMR spectrometer is requested to study the spatial relationships between the catalytic and allosteric sites of these key enzymes in metabolism. Knowledge of the relationship between structure and function in the control of catalysis is basic to understanding normal and abnormal metabolism.