Increased Stability of PEG–PPG Conjugated Human Urokinase against Autolysis

Abstract

Human urokinase (UK) was easily degraded during the incubation at 37°C in a time-dependent manner. The degradation was also observed in the presence of trypsin inhibitors, suggesting that UK was not degraded by exogeneous trypsin-like serine protease but by autolysis. In this cases, the A-chain of UK was selectively degraded. Polyethylene glycol-polypropylene glycol conjugated urokinase (PEG–PPG–UK) was not degraded after prolonged incubation at 37°C. These results demonstrated that PEG–PPG modification completely blocked the degradation of UK by autolysis.

Key words:

• human urokinase
• polyethylene glycol–polypropylene glycol
• chemical modification
• autolysis