电喷雾离子化多级质谱解析环孢菌素结构

Structural characterization of cyclosporins by electrospray ionization mass spectrometry

应用电喷雾离子化多级质谱法分析四种环孢菌素同系物,并对它们的裂解规律进行分析归纳。在电喷雾离子化多级质谱条件下,环孢菌素先形成N端加质子的[M+H]+分子离子,然后沿肽链的酰胺键发生断裂,产生相应的碎片离子,开环裂解主要发生在2和3位、1和11位以及5位和6位氨基酸残基之间。这一裂解规律可应用于环孢菌素类化合物的快速结构鉴定。

Electrospray ionization mass spectrometry method was applied to the structural characterization of cyclosporins, the fragmentation patterns and structural assignments of cyclosporins were discussed. Under the experimental conditions, cyclosporins first form [M＋H]＋ ion by absorbing a proton on the N atom, then the amide bond split and a series of fragments formed. The main fragmentation pathways started by primary splitting between amino acid residues 2-3, 1-11 and 5-6. The corresponding N-terminal b-type ions were common fragment types in the mass spectra. The fragmentation scheme could be used for rapid amino acid sequence determination of cyclosporins.