Characterization and control of an immobilized allosteric enzyme system.

Both immobilization techniques described in this work seem appropriate for this allosteric enzyme. However, the kinetic behavior of the dCMP deaminase trapped in a protein membrane is markedly different from that observed with the enzyme in solution and with the enzyme gelled on an artificial membrane. The enzyme, in fact, in all instances loses its cooperative action toward the substrate and even the allosteric ligands, or they do not affect the activity, or it behaves in a completely different way. In particular, dTTP seems to behave as a noncompetitive inhibitor. These effects can be attributed either to the freezing of the enzyme in one of its conformations or, more generally, to the effect of physical constraints and diffusional resistances. Further studies are in progress to distinguish between the contributions of each one of these phenomena to the kinetic behavior of the enzyme.