Table 1.

Characteristics of the peptides containing the CES1c active site serine (Ser221) that were found to be conjugated to NAc-Cys-linker-drug

Peptide sequenceTheoretical peptide mass (Da)Observed m/z (z) without conjugateObserved m/z (z) with conjugateMost predominant fragment ion m/z
GES221SGG492.19493.19 (1)730.79 (2)681.27
GES221SGGIS691.37692.37 (1)830.85 (2)881.44
GES221SGGISV790.37791.37 (1)880.39 (2)980.50
GES221SGGISVS877.40878.40 (1)923.90 (2)1067.50
IFGES221SGGIS951.45952.45 (1)960.93 (2)1141.62