Table 1

Determination of PEGylation degree of PEGylated rMETase conjugates

The degree of PEGylation of naked and PEGylated rMETase was determined using the fluorescamine assay and MALDI as described in “Materials and Methods.” The results of fluorescamine assay were expressed as the percentage of PEGylated lysine groups in rMETase. The MALDI results were expressed as both the total molecular mass of PEGylated rMETase monomer and the calculated number of conjugated PEG polymers/rMETase monomer. Each PEG polymer attached to rMETase contributes approximately 5 kDa to the total molecular mass of PEGylated rMETase monomer.

Fluorescamine assay (% of lysines conjugated)MALDI
Molecular mass (kDa)PEGs/rMETase monomer
Naked rMETase042.30
PEG/rMETase 303348.3–75.31–6
PEG/rMETase 606159.8–81.03–7
PEG/rMETase 1208182.0–91.97–9