Molecular imaging of biological samples: Localization of peptides and proteins using MALDI-TOF MS
Molecular imaging of biological samples: Localization of peptides and proteins using MALDI-TOF MS
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DOI：
10.1021/ac970888i
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发表时间：
1997-12-01
影响因子：
7.4
通讯作者：
Gile, J
中科院分区：
文献类型：
--
作者：
Caprioli, RM;Farmer, TB;Gile, J
基质辅助激光解吸/电离质谱（MALDI MS）已用于生成一个或多个质荷（m/z）值的样品离子图像，提供将特定分子映射到原始样品的二维坐标的能力，该技术的高灵敏度（蛋白质和肽的低飞摩尔到阿托摩尔水平）允许研究发生在例如哺乳动物组织切片中的有组织的生化过程，质谱仪用于确定分子组织表面层分子的重量，从样品中解吸的分子通常被单质子化，产生 (M + H)(+) 处的离子，其中 M 是分子质量，该过程包括用一薄层能量吸收基质涂覆组织切片或切片的印迹，然后分析样品以产生有序的质谱阵列，每个包含通常覆盖超过 50 000 Da 范围的标称 m/z 值，可以显示图像单个 m/z 值作为选定的离子图像，这将定位组织中的单个化合物，或者作为总离子图像，组织切片的 MALDI 离子图像可以在准备步骤后直接从组织切片中获得，这已通过大鼠胰腺切片中胰岛中所含的胰岛素、大鼠垂体切片中小区域中的激素肽以及与人粘膜细胞膜结合的小蛋白质的映射得到证明。或者，可以通过印迹分析组织的印记特殊制备的目标上的组织切片含有吸附剂材料，例如 C-18 涂层树脂珠、肽和小蛋白质，与 C-18 结合并产生组织的正印记，然后可由质谱仪成像。这通过对大鼠脾脏区域的 MALDI 离子图像分析以及对穿过前部、中间和后部区域的大鼠垂体区域（其中定位了局部肽）的 MALDI 离子图像分析得到了证明。在来自大鼠垂体印迹的前/中叶的单个光谱中，观察到了与该组织中存在的肽相对应的 50 多个离子以及前体、亚型和代谢片段。
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has been used to generate ion images of samples in one or more mass-to-charge (m/z) values, providing the capability of mapping specific molecules to two-dimensional coordinates of the original sample, The high sensitivity of the technique (low-femtomole to attomole levels for proteins and peptides) allows the study of organized biochemical processes occurring in, for example, mammalian tissue sections, The mass spectrometer is used to determine the molecular weights of the molecules in the surface layers of the tissue, Molecules desorbed from the sample typically are singly protonated, giving an ion at (M + H)(+), where M is the molecular mass, The procedure involves coating the tissue section, or a blotted imprint of the section, with a thin layer of energy-absorbing matrix and then analyzing the sample to produce an ordered array of mass spectra, each containing nominal m/z values typically covering a range of over 50 000 Da, Images can be displayed in individual m/z values as a selected ion image, which would localize individual compounds in the tissue, or as summed ion images, MALDI ion images of tissue sections can be obtained directly from tissue slices following preparative steps, and this is demonstrated for the mapping of insulin contained in an islet in a section of rat pancreas, hormone peptides in a small area of a section of rat pituitary, and a small protein bound to the membrane of human mucosa cells, Alternatively, imprints of the tissue can be analyzed by blotting the tissue sections on specially prepared targets containing an adsorbent material, e.g., C-18 coated resin beads, Peptides and small proteins bind to the C-18 and create a positive imprint of the tissue which can then be imaged by the mass spectrometer. This is demonstrated for the MALDI ion image analysis of regions of rat splenic pancreas and for an area of rat pituitary traversing the anterior, intermediate, and posterior regions where localized peptides were mapped, In a single spectrum from the anterior/intermediate lobe of a rat pituitary print, over 50 ions corresponding to the peptides present in this tissue were observed as well as precursors, isoforms, and metabolic fragments.