Peptide analysis using a solid support

The method according to any one of the preceding claims, wherein the amount of unwanted ester side-products after step (a) is reduced or eliminated by adding one or more nucleophilic reagents to the derivatized polypeptide, followed by a washing step.

The method according to any one of the preceding claims, wherein the acidic reagent has a pKa of less than about 2 when coupled to the polypeptide.

The method according to any one of the preceding claims, wherein the mass spectrometric technique used in step (b) is matrix-assisted laser desorption ionization (MALDI) mass spectrometry.

The method according to any one of the preceding claims, wherein the mass spectrometric technique used in step (b) is electrospray ionization (ESI).

The method according to any one of the preceding claims, wherein in step (c), the fragmentation pattern is interpreted using a software program or database.

The method according to any one of the preceding claims, wherein all the steps are conducted as part of an automated or semi-automated procedure.

The method according to any one of the preceding claims, wherein the activated acid moiety is an N-hydroxysuccinimide (NHS) ester.

The method according to any one of the preceding claims, wherein the reagent comprises a 3-sulfopropionic acid N-hydroxysuccinimide ester.

The method according to any one of the preceding claims, wherein the polypeptide has been obtained by enzymatic digestion.

The method according to any one of the preceding claims, wherein step (a) is performed during centrifugation of polypeptide and reagent.

The method according to any one of the preceding claims, which further comprises a step of protecting lysine residues prior to the sulfonation step.

The method according to any one of the preceding claims, which comprises a step of protecting lysine residues before the sulfonation according to step (a), which protection is also performed on peptide(s) and/or polypeptide(s) immobilized to a solid support.

A method of protecting lysine residues of peptides and/or polypeptides during a reaction for sulfonation thereof, wherein the peptides are immobilized to a solid support and guanidinated as immobilized before said reaction.

A reagent suitable for use in peptide derivatization methods wherein the polypeptide is immobilized to a solid support, which reagent is selected from the group consisting of 3-sulfopropionic acid N-hydroxysuccinimide ester and 2-sulfobenzoic acid N-hydroxysuccinimide ester.

A kit for identifying a polypeptide by a mass spectrometric technique, which kit comprises at least one reagent in the form of a sulfonyl or sulfonic acid moiety coupled to an activated acid moiety in a container, which reagent exhibits a half-life in aqueous solution of not less than 10 minutes, preferably not less than about 20 minutes and most preferably not less than about 30 minutes at RT.