论文部分内容阅读
应用傅里叶变换离子回旋共振质谱(FT-ICR-MS)的电子捕获解离(ECD)技术对寡糖异构体进行识别.以麦芽七糖、甘露六糖和昆布六糖为研究对象,通过在样品中添加过渡金属离子(Na+、Ca2+、Ba2+、Mg2+、Mn2+和Co2+),研究不同金属离子对寡糖碎裂的影响.加合Ba2+和Ca2+后的麦芽七糖得到了相同的碎裂离子(0,2 A和2,4 A),Mg2+和Mn2+也具有相似的影响(0,2 A、2,4 A和2,5 A),Co2+加合的麦芽七糖也得到了3个交叉环断裂离子(1,4 A、2,4 A和2,5 A),但对于加合Na+后的麦芽七糖仅得到了一个交叉环断裂离子(0,2 A).研究发现,六聚糖的质谱图的信号比相应的麦芽七糖的信号差,应是缔合的金属离子的数量不同导致的结果;区分寡糖异构体比较好的金属离子为Ca2+、Co2+和Mg2+,其中Ca2+是区分寡糖异构体的更可靠的电荷载体.“,”Oligosaccharide isomers were distinguished by electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry ( ECD-FT-ICR-MS ) in combination with utiliZing alkali, alkaline earth, and transition metals ( Na+, Ca2+, Ba2+, Mg2+, Mn2+ and Co2+) as charge carriers in electrospray.Maltoheptaose, mannohexaose and laminarihexaose were taken as examples to investigate influence of metal ions on the extent of oligosaccharide fragmentation.The same types of fragmentation ions ( 0,2 A and 2,4 A) were obtained for barium- and calcium-adducted maltoheptaose.Mg2+ and Mn2+ had the similar influence ( 0,2 A, 2,4 A and 2,5 A ).Three cross-ring cleavage ions ( 1,4 A, 2,4 A and 2,5 A ) were generated in the spectrum of cobalt-associated maltoheptaose.But in the case of doping Na+into maltoheptaose, only 0,2 A ion was detected.It was found that the signals in the spectra of mannohexaose and laminarihexaose were worse than that in the spectrum of maltoheptaose, probably resulting from different numbers of adducted metal ions.The isomers, mannohexaose and laminarihexaose could be distinguished by ECD-MS in conjunction with the addition of Ca2+, Mg2+ or Co2+.The addition of Ca2+ was the best choice for analysis of oligosaccharides.