Improved stability of urease upon coupling to alkylamine and arylamine glass and its analytical use

Biocatalyst stability is a major concern in almost all bioprocesses, because it may affect the overall cost of the process. Immobilization is a cost-effective approach and in the present work, pigeonpea urease was covalently coupled to alkylamine glass via glutaraldehyde activation and arylamine glass via diazotation. This coupling resulted in 92.5% and 90% immobilization, respectively. The immobilized urease showed optimum activity at 77 °C and retained 50% of its activity when incubated at this temperature for 90 min. This immobilized enzyme was quite stable at higher temperatures and over a broad pH range; unusually stable upon storing at 4 °C and also retained 50% activity even after 25 reuses. Hence, the obtained results are much better compared to other matrixes used so far for urease immobilization. This preparation was also successfully used in potentiometric biosensing for the estimation of blood urea from clinical patients. Hence, coupling of urease to glass via this mode of coupling could therefore be a versatile tool for immobilization of proteins and would have great promise in clinical as well as industrial use.