Hayashi A, Matsubara T, Morita M, Kinoshita T, Nakamura T
Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka.
J Biochem. 1989 Aug;106(2):264-9. doi: 10.1093/oxfordjournals.jbchem.a122842.
The structures of intact choline phospholipids were determined by positive and negative ion mode fast atom bombardment mass spectrometry, tandem mass spectrometry, and B2/E and B/E constant linked scan mass spectrometry. The molecular weight of the choline lipid could be clearly determined by the appearance of [M + H]+ or [M + Na]+ in the positive ion mode and triplet ions, e.g., [M - 15]-, [M - 60]-, and [M - 86]-, in the negative ion mode. The structures of the triplet ions were assigned to [M - CH3]-, [M - HN(CH3)3]-, and [M - CH2 = CHN(CH3)3]-, respectively, by the MS/MS of each triplet ion, and the origin of the triplet ions was found as the matrix-ion adduct to the target molecule by using the B2/E linked scan technique. The polar group could be identified by the existence of ions indicating glycerophosphocholine and its cleavage products and by the presence of the triplet ions in the negative ion mode. Positional determination of the distribution of constituent fatty acyl groups was carried out by comparing the intensity of deacylated ions from positions 1 and 2 in the positive ion mode and of the ions produced by MS/MS of the triplet ions. From the mass number of the [RCOO]- ion which appeared in the negative ion mode, the molecular weight and degree of unsaturation of the fatty acyl group were determined. The position of double bond(s) in the acyl group was determined from the MS/MS of the [RCOO]- ion.
完整胆碱磷脂的结构通过正离子和负离子模式的快原子轰击质谱、串联质谱以及B2/E和B/E恒定连接扫描质谱来确定。在正离子模式下，通过[M + H]+或[M + Na]+的出现以及在负离子模式下通过三重峰离子，例如[M - 15] -、[M - 60] -和[M - 86] -，可以清楚地确定胆碱脂质的分子量。通过对每个三重峰离子进行串联质谱分析，将三重峰离子的结构分别归属为[M - CH3] -、[M - HN(CH3)3] -和[M - CH2 = CHN(CH3)3] -，并且通过使用B2/E连接扫描技术发现三重峰离子的来源是目标分子与基质离子的加合物。通过存在指示甘油磷酸胆碱及其裂解产物的离子以及在负离子模式下存在三重峰离子，可以识别极性基团。通过比较正离子模式下来自1位和2位的脱酰化离子的强度以及三重峰离子的串联质谱产生的离子强度，来进行组成脂肪酸酰基分布的位置测定。从负离子模式下出现的[RCOO] -离子质量数，确定脂肪酸酰基的分子量和不饱和度。通过[RCOO] -离子的串联质谱确定酰基中双键的位置。
