AN ENGINEERING ANALYSIS FOR THE CONTINUOUS REACTOR BEHAVIOR OF ALPHA-CHYMOTRYPSIN-IMMOBILIZED THERMOSENSITIVE GEL CYLINDERS

In this study, alpha-chymotrypsin was immobilized via physical entrapm ent within thermally reversible isopropylacrylamide-hydroxyethylmethac rylate copolymer gel cylinders. The enzyme-containing gel cylinders we re prepared by a redox polymerization procedure and characterized by e lectron microscopy and equilibrium swelling studies in the hydrolysis medium. The performance of the thermosensitive enzyme-gel system was i nvestigated in a continuous stirred reactor operated at steady-state c onditions. The results indicated that the observed hydrolysis rate of the synthetic substrate (i.e. benzoyl-L-tyrosine ethyl ester) could be controlled by the thermosensitive properties of the carrier matrix. T he maximum value of the observed hydrolysis rate was obtained at 30 de grees C with the enzyme-gel system in the continuous reactor while the free enzyme exhibited maximum activity at 40 degrees C in the batch o ne. A mathematical model was proposed to explain the kinetic behavior of the thermally reversible enzyme-gel cylinders. By the application o f model, the effective diffusion coefficient of substrate within the g el matrix was calculated for different reaction temperatures. Thiele m odulus and effectiveness factor values for the enzyme-gel system were also estimated. A sudden increase in the Thiele modulus of the enzyme- gel system at the lower critical solution temperature of the gel matri x (i.e. 35 degrees C) was first shown, experimentally. The effectivene ss factors determined at different reaction temperatures indicated tha t the overall hydrolysis rate was controlled by the mass transfer resi stance within the gel matrix. (C) 1998 Elsevier Science B.V. All right s reserved.