Mass Spectrometry Data Center, Biomolecular Measurement Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899-8362 , United States.
Anal Chem. 2018 Aug 7;90(15):8977-8988. doi: 10.1021/acs.analchem.8b01176. Epub 2018 Jul 17.
We report the development and availability of a mass spectral reference library for oligosaccharides in human milk. This represents a new variety of spectral library that includes consensus spectra of compounds annotated through various data analysis methods, a concept that can be extended to other varieties of biological fluids. Oligosaccharides from the NIST Standard Reference Material (SRM) 1953, composed of human milk pooled from 100 breastfeeding mothers, were identified and characterized using hydrophilic interaction liquid chromatography electrospray ionization tandem mass spectrometry (HILIC-ESI-MS/MS) and the NIST 17 Tandem MS Library. Consensus reference spectra were generated, incorporated into a searchable library, and matched using the newly developed hybrid search algorithm to elucidate unknown oligosaccharides. The NIST hybrid search program facilitates the structural assignment of complex oligosaccharides especially when reference standards are not commercially available. High accuracy mass measurement for precursor and product ions, as well as the relatively high MS/MS signal intensities of various oligosaccharide precursors with Fourier transform ion trap (FT-IT) and higher energy dissociation (HCD) fragmentation techniques, enabled the assignment of multiple free and underivatized fucosyllacto- and sialyllacto-oligosaccharide spectra. Neutral and sialylated isomeric oligosaccharides have distinct retention times, allowing the identification of 74 oligosaccharides in the reference material. This collection of newly characterized spectra based on a searchable, reference MS library of annotated oligosaccharides can be applied to analyze similar compounds in other types of milk or any biological fluid containing milk oligosaccharides.
我们报告了一种人乳寡糖质谱参考文库的开发和可用性。这代表了一种新的光谱文库种类，其中包括通过各种数据分析方法注释的化合物的共识光谱，这一概念可以扩展到其他种类的生物流体。使用亲水相互作用液相色谱电喷雾串联质谱（HILIC-ESI-MS/MS）和 NIST 17 串联 MS 库，对 NIST 标准参考物质（SRM）1953 中的寡糖进行了鉴定和表征，该 SRM 由来自 100 位母乳喂养母亲的人乳混合而成。生成了共识参考光谱，将其合并到可搜索的库中，并使用新开发的混合搜索算法进行匹配，以阐明未知的寡糖。NIST 混合搜索程序有助于复杂寡糖的结构分配，特别是当参考标准不可用时。前体和产物离子的高精度质量测量，以及傅里叶变换离子阱（FT-IT）和更高能量解离（HCD）碎裂技术对各种寡糖前体的相对较高的 MS/MS 信号强度，使多种游离和未衍生化的岩藻糖基和唾液酸基乳糖寡糖谱得以分配。中性和唾液酸化的异构体寡糖具有不同的保留时间，从而能够鉴定参考物质中的 74 种寡糖。基于可搜索的、注释寡糖的参考 MS 库的这些新表征的光谱集合可以应用于分析其他类型的乳或任何含有乳寡糖的生物流体中的类似化合物。
