In general, PEGylated α-MMC and PEGylated MAP30 can be obtained in the following optimal conditions: 10 mg/mL of α-MMC or MAP30 reacted with (mPEG) 2 -Lys-NHS (mass ratio of PEG:RIP was 2:1) in pH 8.5,100 mM borate buffer at room temperature for 30 minutes. The reaction mixture was applied with Sephacryl S-100 column. The PEGylated conjugates can be collected and assessed by gradient SDS-PAGE and MALDI-TOF-MS.