生长抑素一级结构的电喷雾质谱分析

目的生长抑素的分子量及其一级结构的测定。方法应用电喷雾质谱法(ESI-MS)测定了环肽药物生长抑素的分子量,用2-巯基乙醇将生长抑素的双硫键还原,再用源内碰撞诱导解离技术进行测定,根据其典型碎片离子确证其氨基酸序列。结果测得生长抑素准分子离子峰［M+H］⁺ m/z 1 637.8, ［M+Na］⁺ m/z 1 659.5及［M+2Na-H］⁺ m/z 1 681.5,［M+2H］²⁺ m/z 819.5及［M+H+Na］²⁺ m/z 830.3,表明生长抑素的分子量为1 636.7,与理论值一致。将双硫键还原后,用CID技术进行测定,得到了一系列y和b系列的特征碎片离子,证实生长抑素还原产物的氨基酸序列为A-G-C-K-N-F-F-W-K-T-F-T-S-C。结论用ESI-MS法测得的生长抑素的分子量及一级结构与理论值相符。

Determination of first-order structure of somatostatin by electrospray ionization mass spectrometry

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 in source 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.