Patent ID: 7700306

Claim:
A method for characterising a polypeptide, which method comprises the steps of: (a) cleaving the polypeptide with a sequence specific cleavage reagent to form peptide fragments; (b) capping one or more ε-amino groups that are present with a lysine reactive agent; (c) analyzing the peptide fragments by (a) labelling the analyte with a light-absorbing label that absorbs light at a predetermined frequency, to form a labelled analyte; (b) embedding the labelled analyte in a matrix wherein the matrix comprises at least one light-absorbing compound, to form an embedded labelled analyte; (c) desorbing the embedded labelled analyte by exposing it to light having the predetermined frequency, to form a desorbed analyte; and (d) detecting the desorbed analyte by mass spectrometry, to characterise the analyte to form a mass fingerprint for the polypeptide; and (d) determining the identity of the polypeptide from the mass fingerprint.