PEPTIDE SEQUENCING BY PARTIAL ACID-HYDROLYSIS AND HIGH-RESOLUTION PLASMA DESORPTION MASS-SPECTROMETRY

A method of deriving peptide sequence information using partial acid h ydrolysis in combination with accurate mass measurements and immonium ion analysis provided by high-resolution plasma desorption mass spectr ometry has been developed. The technique is very simple in terms of th e chemistry and involves a short-time (3-30 min) incubation of the pep tide in 1N-6N HCl at 100-110 degrees C with subsequent mass spectromet ric analysis. Partial acid hydrolysis is found to produce sequence-spe cific segments, often ladder-like, although not always a complete set. Two application examples of the method are given: the linear peptide bradykinin and desmopressin, a peptide with an internal S-S bond and a non-amino-acid constituent. The technique has proved to be particular ly useful in cases where some a priori information on the peptide stru cture was already known or where the automated Edman degradation techn ique might yield erratic results or not work at all.