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Updated: Aug 17, 2026

Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
[Determination of first-order structure of somatostatin by electrospray ionization mass spectrometry]
Hong-hua Zhou1, Ren-ling Ma, Long-sheng Sheng
1Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China. Honghua.zhou@sohu.com
Aim:
To determine the molecular weight and first-order structure of somatostatin.
Methods:
The molecular weight of somatostatin was determined by electrospray ionization mass spectrometry. Somatostatin was deoxidized by 2-mercaptoethanol. A series of typical fragment ions of deoxidized product were obtained by insource collision-induced dissociation (CID).
Results:
The m/z of quasi-molecular ion [M + H]+ of somatostatin was 1,637.8 and [M + Na]+ was 1,659.5. The m/z of double-charge ion [M + 2H]2+ was 819.5 and [M + H + Na]2+ was 830.3. It showed that the molecular weight of somatostatin was 1,636.7. The y and b series of fragment ions of deoxidized product were obtained by adjusting the fragmentor voltage. It was determined that the first-order structure of deoxidized product of somatostatin was A-G-C-K-N-F-F-W-K-T-F-T-S-C.
Conclusion:
The molecular weight and first-order structure of somatostatin were confirmed.
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