[Determination of first-order structure of somatostatin by electrospray ionization mass spectrometry].
OBJECTIVE
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.


CONCLUSIONS
The molecular weight and first-order structure of somatostatin were confirmed.
Zhou
Hong-hua
HH
Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China. Honghua.zhou@sohu.com
Ma
Ren-ling
RL
Sheng
Long-sheng
LS
Xiang
Bing-ren
BR
An
Deng-kui
DK
D000595:Amino Acid Sequence; D015394:Molecular Structure; D008970:Molecular Weight; D013004:Somatostatin / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D013004:Somatostatin