Characterization of synthetic N-acetylcysteine conjugates by positive- and negative-ion 252Cf plasma desorption mass spectrometry

✍ Scribed by Ernst Pittenauer; Anton Pachinger; Günter Allmaier; Erich R. Schmid

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 495 KB
• Volume: 26
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210261207

✦ Synopsis

Dedicated to Professor Dr G. SpiteUer on the occasion of his 60th birthday N-Acetylcysteine and nine N-acetylcysteine conjugates of synthetic origin were characterized by positive-and negative-ion plasma desorption mass spectrometry. For sample preparation the electrospray technique and the nitrocellulose spin deposition technique were applied. The fkagmentation of these compounds, which are best seen as S-substituted desaminoglycylcysteiae dipeptides, shows a similar behaviour to that of linear peptides. In the positive-ion mass spectra intense protonated molecular ion peaks are observed. In addition, several sequence specific fragment ions (A+, B+, IY + 2H]+, Z'), immonium ions (I+) and a diagnostic fragment ion for mercap turic acids %+) are detected. The negative-ion mass spectra exhibit deprotonated molecular ions and in contrast only one fragment ion corresponding to sidechain specific cleavage ([ R,S] -) representing the xenobiotic moiety.

In the case of a low alkali metal concentration on the target, cluster molecular ions of the [nM + HI+ or InM -H]ion type (n = 1-3) are observed. The analysis of an equimolar mixture of eight N-acetylcysteine conjugates shows diaerent quasi-molecular ion yields for the positiveand negative-ion spectra.