Could you send me either the chemistry used or the exact structure of the linkage between the PEG and the protein in Peg20K-Amine-Ax15?
We isolated and sequenced the new peptide (152') observed in the tryptic map of this material. The odd thing was that the main sequence observed started at the SECOND amino acid of the N-terminal peptide, i.e. FTEH....
>From a naive point of view, this peptide should have been blocked from participating in the sequencing reactions.
I'd like the structure of the linkage to see if cleavage of the N-terminal alanine/PEG could be rationalized in the Edman degradation reactions.
In this peak, we're also seeing evidence of pegylation at lysine-45; the ..ADGMP.. of peptide 9 shows up at the appropriate position as if the proteolytic position at lysine-45 were eliminated.
Vernon