Table 1. Characteristics of unmodified rCU, PEG reagent and PEGylated rCU proteins.
| Items | mPEG-rCU-1 | mPEG-rCU-2 | mPEG-rCU-3 | |
| Unmodified uricase properties | Tetramer content | >99.8% | 9.8% | >99.8% |
| Enzymatic activity(U/mg) | 11.2±0.6 | 9.3±0.4 | 11.2±0.6 | |
| PEG reagent properties | PEG Diol content | <0.2% | <0.2% | 2.7% |
| PEGylated uricase properties | Modification degreea | 9.9±0.5 | 9.7±0.6 | 10.3±0.6 |
| Enzymatic activity(U/mg) | 9.8±0.7 | 6.7±0.5 | 9.6±0.6 | |
| Enzymatic retention | 87.5%±5.6% | 72.0%±4.6% | 85.7%±6.3% | |
a
modification degree: number of 5 kDa mPEG chains that coupled to each uricase monomer.