Harvey David J, Martin Rachel L, Jackson Kathryn A, Sutton Chris W
Oxford Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK.
Rapid Commun Mass Spectrom. 2004;18(24):2997-3007. doi: 10.1002/rcm.1709.
N-Linked glycans were ionized from several matrices with a Shimadzu-Biotech AXIMA-QIT matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometer. [M+Na]+ ions were produced from all matrices and were accompanied by varying amounts of in-source fragmentation products. The least fragmentation was produced by 2,5-dihydroxybenzoic acid and the most by alpha-cyano-4-hydroxycinnamic acid and 6-aza-2-thiothymine. Sialic acid loss was extensive but could be prevented by formation of methyl esters. Fragmentation produced typical low-energy-type spectra dominated by ions formed by glycosidic cleavages. MS(n) spectra (n = 3 and 4) were used to probe the pathways leading to the major diagnostic ions. Thus, for example, an ion that was formed by loss of the core GlcNAc residues and the 3-antenna was confirmed as being formed by a B/Y rather than a C/Z mechanism. The proposed structures of several cross-ring cleavage ions were confirmed and it was shown that MS3 spectra could be obtained from as little as 10 fmol of glycan.
使用岛津生物技术公司的AXIMA-QIT基质辅助激光解吸/电离四极杆离子阱飞行时间质谱仪，从几种基质中对N-连接聚糖进行电离。所有基质均产生[M+Na]+离子，并伴有不同量的源内碎片产物。2,5-二羟基苯甲酸产生的碎片最少，α-氰基-4-羟基肉桂酸和6-氮杂-2-硫代胸腺嘧啶产生的碎片最多。唾液酸损失广泛，但可以通过形成甲酯来防止。碎片产生典型的低能型光谱，主要由糖苷键裂解形成的离子主导。MS(n)光谱（n = 3和4）用于探究导致主要诊断离子的途径。因此，例如，通过失去核心GlcNAc残基和三天线形成的离子被确认为是通过B/Y而非C/Z机制形成的。几种跨环裂解离子的推测结构得到了证实，并且表明从低至10 fmol的聚糖即可获得MS3光谱。
