NEGATIVE-ION ELECTROSPRAY TANDEM MASS-SPECTROMETRY OF PEPTIDES DERIVATIZED WITH 4-AMINONAPHTHALENESULPHONIC ACID

The value of derivatizing peptides at the C-terminus with 4-aminonapht halenesulphonic acid (ansa) to aid in the de novo sequencing of peptid es by mass spectrometry was assessed. Negative-ion electrospray of pep tides is enhanced by derivatization with ansa. The derivatizing group also has the effect of increasing the mass of the peptides by 205 Da, often shifting their deprotonated molecules to regions of the mass spe ctrum with reduced chemical noise. Collision-induced dissociation of n aphthalenesulphonated peptide [M - H](-) ions results in abundant frag ment ions formed by charge-remote fragmentations. The resulting fragme ntation patterns are less complex than those of the underivatized anal ogues and are easier to interpret. Peptides were successfully derivati zed at the low picomole level and sequenced on the hundred femtomole l evel using nano-electrospray tandem mass spectrometry. (C) 1998 John W iley & Sons, Ltd.