Immobilization of glucose isomerase onto granular chicken bone

Abstract
Glucose isomerase was immobilized onto granular chicken bone (BIOBONE™) by adsorption. The amount of activity bound relative to an equal amount of free enzyme was 32™1%, with the estimated specific activity decreasing from ll.l™0.7 to 3.9™0.5 U/mg protein with immobilization. Compared with the free enzyme, immobilized glucose isomerase showed a threefold increase in theKm for fructose and a fivefold decrease in Vmax. High operating temperatures were possible (>55™C), but continuous use and long-term storage studies showed gradual losses of activity. Both the binding and the activity of the bone-immobilized enzyme were highly resistant to treatments with detergent, ethanol, and KC1. Studies to determine mass transfer limitation effects on immobilized glucose isomerase showed that these were insignificant for this system.