OBJECTIVE: To characterize the catalytic properties of selected enzymes at cellular concentrations (0.01 - 10 mg/ml) in order to reveal and explain any altered properties at these high enzyme concentrations from those obtained previously with dilute enzyme solutions (usually less than 0.00l mg/ml) and to relate these findings to metabolic regulation at the enzyme level. Enzymes to be studied: Enzymes currently being studied are rat liver glucose 6-phosphate dehydrogenase, porcine liver phosphofructokinase, and chicken liver pyruvate carboxylase. BIBLIOGRAPHIC REFERENCE: Thompson, R.E., Spivey, H.O., and Katz, A.J. (1976) "Rat Liver Cytoplasmic Glucose-6-Phosphate Dehydrogenase. Steady-State Kinetic Properties and Circular Dichroism", Biochemistry 15, 862-867.