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Abstract
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Urate oxidase (UOX) is used for the treatment of hyperuricemia and gout. The low stability of protein drugs such
as UOX is a significant drawback in their liquid solutions. In this study, UOX from Aspergillus flavus was overexpressed
and purified. Then, the effect of osmolytes (glycerol, sorbitol, and sucrose) on UOX thermal stability
was studied. The enzyme stability was optimized by the aid of osmolytes using response surface methodology
(RSM). The thermal stability results and Pareto analysis showed that sucrose has a stronger stabilization effect on
UOX relative to the other osmolytes and increases the enzyme stability up to 2.4-fold, solely. RSM results indicated
that the stability of UOX increased up to 4.9-fold in the presence of 12 % of glycerol and sucrose. The
combinatorial effect results indicated that the osmolytes affect each other stabilization effects on UOX, probably
through influencing the hydrogen bonds and mixing the osmolytes at different concentrations does not always
lead to increased stability of UOX. The results revealed that the effect of sorbitol on UOX stability was negligible
in the presence of glycerol and sucrose. Finally, this study results showed that RSM can be used to select a proper
set of osmolytes for enzyme stabilization.
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