Fig. 7.

Identification of the PEGylation sites in amylin. a MALDI-ToF-MS analysis of tryptic digests from PEGylated amylin. mPEG-SC was allowed to react with amylin (10:1) for 4 h, and the reaction was resolved by SDS-PAGE. Bands were removed from the gel and digested with trypsin for further MALDI-ToF-MS analysis of the resulting peptides. Inset, SDS-PAGE analysis of the reaction products and an indication of the excised bands (labeled #1 and #2) used for tryptic digestion. b MALDI-ToF-MS analysis of free mPEG-SC-NHS. c MALDI-ToF-MS analysis of free mPEG-SPA-NHS. The calculation of the average molecular number (Mn) and the average molecular weight from the MALDI-ToF-MS analysis is shown in Table II. The details are described in the “MATERIAL AND METHODS” section