Affinity precipitation could be a viable alternative to conventional protein purification techniques with advantages of easy scale-up, cost and time effectiveness. We have used alginate as the affinity matrix for entrapment of a-amylase and subsequent precipitation of the beads with calcium
chloride. Amylase was recoverable by addition of 0.5 M NaCl containing 0.2 M Ca2+. The Enzyme was found to be homogenous (recovery of 76%) with a specific activity of 1764 U/mg. The pH and temperature optima shifted (on entrapment) from 5.5 to 6.0 and 54 to 60C, respectively. The entrapped enzyme had higher thermal stability compared to the free enzyme. The midpoint of thermal inactivation for the enzyme increased by 61C on entrapment. The entrapped enzyme had an
Ea value of 51.7 compared to 40.9 kcal mol1 for the free enzyme. The positive increase in
Ea value as well as the half-life of the entrapped enzyme is indicative of increased stability. The reusability of the beads was dependent on bead size. Beads with