Immobilization of invertase in germania matrix and a study of its enzymatic activity

Abstract

Invertase from baker yeast was entrapped within germania nanospheres. The enzyme was incorporated simultaneously during the precipitation of germania using the peptide sequence T-G-H-Q-S-P-G-A-Y-A-A-H that is known to catalyze the formation of germania. The efficiency of immobilization and its activity under different conditions, operation and storage stability were studied. The enzyme was entrapped efficiently and was found to be stable and retained activity over a longer period of time compared to that of the free enzyme in solution. The effect of temperature and pH on the activity of the enzyme showed that the entrapped enzyme remained stable and active over a temperature range of 15–65 °C. Optimum activity of the immobilized invertase was found to be at 60 °C. In addition, the immobilized enzyme remained active over a broader pH range (4.5–6.5). Thus germania nanospheres can efficiently immobilize enzymes and remain stable over a range of temperatures. Such immobilization techniques protect the enzyme from harsh environments required during chemical synthesis and functionalization methods. The ability to trap biomolecules such as enzymes in germania nanospheres gives rise to a new class of materials with a variety of applications such as biosensors and bioactive glasses.