Study on stability of N-terminal site-specific PEGylated uncase / 中国生化药物杂志

ABSTRACT

Purpose The research was conducted to evaluate the stability of N-terminal site-specific PEGylated uricase. Methods The enzyme activity is used as an index to evaluate the thermal stability (at 4-80 ℃) , the pH stability, the ability of avoiding the trypsin digestion and half-life in vivo of PEG-uricase, then it is compared with uricase. Results PEGylated uricase is thermally more stable than uricase between 4 ℃ and 60 ℃, but at 70 ℃, the enzyme activity of both PEG-uricase and uricase decreases sharply. In the test of pH stability, the curve of uricase shows an obvious decrease of enzyme activity at 5 .2-6.0 and 9.2-10.0. The behavior of PEG-uricase indicates that the destabilizing was prevented effectively by PEGylation. The test of anti-trypsin digestion suggests that PEG-uricase retains 70% of its enzyme activity,but uricase only 20% ,200 minutes after being reserved in trypsin solution. Stability in vivo indicates that the half-life of PEG-uricase is 1 530 min and uricase, only 45 min. Conclusion PEGylated uricase has improved thermal stability, the pH stability, ability of protecting from trypsin digestion and stability in vivo.