Effect of temperature gradients on the activity of enzymes immobilized on natural polymeric matrices.

The invertase activity has been studied in the presence of a temperature gradient by interposing the enzyme onto a polymeric membrane between two solutions, kept at different temperatures. The enzyme activity has been determined as a function of average temperature (T(av)) and of the applied temperature difference DELTAT= T(w) - T(c). It has been found that in the non-isothermal state the activity is higher than in comparable isothermal conditions, the increase being proportional to the applied transmembrane temperature difference. Mathematical relationships between the isothermal and non-isothermal enzyme activity have been derived. The rapid product removal from the enzyme complex by means of a process of matter transport associated to the flux of thermal energy is indicated as the way by which the temperature gradient affects the enzyme activity. Some practical applications are suggested.