Dextrin-uricase conjugate: Preparation, characterization, and enzymatic properties

Uricase was conjugated with dextrin to improve its stability. Firstly, dextrin was succinylated into dextrin monosuccinate with the functional group, carboxylic acid, and dextrin monosuccinates with different degree of substitution (DS) were prepared. Secondly, dextrin-uricase conjugate was synthesized by uricase and dextrin monosuccinate, which was verified by size-exclusion chromatography and anion exchange chromatography. Thirdly, it was found that the conjugate degree of the dextrin-uricase conjugate was positively related to the DS of dextrin monosuccinate, but the activity was seriously lost and difficult to recover by α-amylase. When the molar ratio of dextrin monosuccinate (DS = 0.283) to uricase was 30:1, the conjugate degree of dextrin-uricase conjugate reached 22.1% and the activity was decreased to 40.4%. After triggered by α-amylase, the activity was recovered to 83.4%. Finally, the enzymatic properties of this dextrin-uricase conjugate were investigated and compared with those of free uricase. The optimal pH and temperature of the dextrin-uricase conjugate was 9.0 and 45 °C, respectively, whereas the optimal pH and temperature of free uricase was 8.5 and 45 °C, respectively. Furthermore, dextrin-uricase conjugate was more resistant to simulated physiological conditions and trypsin. These results suggested that the stability of uricase could be ameliorated by conjugation with dextrin.