Our objectives are to charcterized the catalytic properties of enzymes that associate to form enzyme complexes at cellular enzyme concentrations. The prevalence and catalytic consequences of polymer induced enzyme associations (cf. Fakien and Kmiotek (1979) J. Biol. Chem. 254, 5983 and Herzog and Weber (1978) Eur. J. Biochem. 91, 249) are of primary interest. The kinetic properties of these associated enzyme complexes are to be measured with fast kinetic methods and compared with those obtaining conventional methods (dilute and dissociated complexes) and those obtained with the enzymes in situ using permeabilized cells and organelles.