The luciferase from the fireflies luciola mingrelica was immobilized on different CNBr-activated polysaccharide carriers, e. g. Sepharose, Ultrodex, cellophane, Ultrogel. The catalytic activity and the inactivation rate constants of the soluble and immobilized enzyme at 25 degrees (pH 6.0--9.0) were determined. During immobilization on Sepharose the pH profile of activity shifts towards lower pH values, while upon immobilization on Ultrogel and Ultrodex it is considerably broadened. Immobilization on Ultrogel and Ultrodex results in a 3--100 -fold stabilization of the enzyme (pH less than 7.5). whereas the stability of luciferase immobilized on Sepharose and cellophane within the same pH range is 10--1000 times higher than that of the soluble enzyme. It was shown that inactivation of luciferase immobilized on Sepharose and cellophane is limited by oxidation of the SH-groups of the enzyme and is inhibited by dithiothreitol. The inactivation of luciferase immobilized on Ultrogel and Ultrodex and that of soluble enzyme is not limited by oxidation of the SH-groups.
Animals Coleoptera