IMMOBILIZATION OF L-RHAMNOSE ISOMERASE AND ITS APPLICATION IN L-MANNOSE PRODUCTION FROM L-FRUCTOSE

a constitutive L-rhamnose isomerase (L-RI) from Pseudomonas sp. strain LL172 was immobilized an various types and sizes of chitopearl beads. The highest activity yield (80%) observed was that of L-RI immobilize d on chitopearl heads BCW 2603. The pH range for optimal activity and stability of the immobilized enzyme (pH 5-11) was found to be broader than that for free enzyme. The temperature for optimal activity (60 de grees C), and the thermal stability (stable at 60 degrees C for 10 min ) were similar to that of the free enzyme. However, immobilized enzyme as well as free enzyme required manganese ions for maximum activity. At equilibrium, the production of L-mannose from L-fructose was determ ined to be 30%, and the time required to reach equilibrium was inverse ly proportional to the amount of immobilized enzyme added. Thus, L-man nose could be prepared on a large scale simply by increasing the initi al amounts of the reaction components. Moreover, the immobilized enzym e retained about 90% of the initial activity even after five repeated uses in a batch reaction.