P-9 質量分析法を基盤とする環状ペプチドの構造解析法(ポスター発表の部)

元データ 2007-08-24


Fragment ions obtained by MS/MS technique was quite effective for the amino acid sequencing for linear peptides. However, in the case of cyclic peptides, fragmentation pattern was complicated because the cleavages occurred randomly and fragment ions were generated as a_n, b_n, c_n, x_n, y_n and z_n series ions, so we have never obtained sufficient sequence information. In order to overcome this problem we have made attempt to apply the ion trap LC/MS with MS^n technique and characterized the fragment ions obtained from microcystins, anabaenopeptins and aeruginopeptins as the cyclic peptides. In the case of anabaenopeptins, MS^2 analysis did not provide enough sequence information of the cyclic structure and the MS^3 analysis was applied to the sequencing of the constituent amino acids. The diagnostic fragment ions were obtained by the MS^3 analysis and these ions were quite effective to obtain the sequence information of constituent amino acid. Meanwhile, MS^2 analysis was enough to obtain the sequence information of microcystins and aeruginopeptins. In any case, resulting fragment ions obtained from the cyclic structure were formed by way of the two-bond fission mechanism of the precursor ion, in which an initial fission of the cyclic structure to a linearized one and subsequent fission(s) at the peptide bonds are included. Moreover, their fragmentation showed the similar pattern among the structure related compounds, indicating that the cleavages occurred at definite peptide bonds. In addition, the resulting fragment ions are generated as b_n series ions and the mass difference facilitates the amino acid sequencing. Consequently, ion trap LC/MS with MS^n technique provide informative sequence information and the resulting fragment ions are reproducible among the structure related compounds and reliable for the sequencing of constituent amino acid of the cyclic structure. Finally, we would like to propose a structural analysis method for cyclic peptide based on ion trap LC/MS technology, in which advanced Marfey's method and MS^n techniques with two-bond fission mechanism are included.


原田 健一 名城大院総合学術:名城大薬
加藤 創 名城大院総合学術
真弓 剛 名城大院総合学術
川崎 好人 名城大院総合学術
長谷川 真照 名城大院総合学術