Thermostability of immobilized plant microsomes

Microsomes from grapewine (V. vinifera L. cv. Camay Fréaux) cell homogenates were immobilized in calcium alginate beads. Cinnamic acid-4-hydroxylase activities for both freely suspended and immobilized microsomes were compared, resulting in a decrease of 30–40% of the initial activity as a consequence of immobilization. This decrease was probably due to both protein denaturation and microsomal mass losses during the gelation process. Nevertheless, immobilized microsomes showed an enhanced thermostability. Only 35% of the initial activity was lost when immobilized microsomes were incubated at 45°C for 10 minutes, whereas a 68% activity loss was observed when dealing with free microsomes.