Lehmann W D, Bohne A, von Der Lieth C W
Central Spectroscopy, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.
J Mass Spectrom. 2000 Nov;35(11):1335-41. doi: 10.1002/1096-9888(200011)35:11<1335::AID-JMS70>3.0.CO;2-0.
Analytically useful information from accurate mass data for peptides with an error of </=20 ppm is discussed. The deltamass (= mass value following the decimal point) distribution of natural peptides is extracted from a protein database. Compared with the random peptide data, the natural data show a higher average deltamass value and a smaller width of the mass distribution. This deviation can be ascribed to the non-random abundances of the standard amino acids. In particular, accurate mass data for peptides located near the edges of the natural mass distribution contain analytical information. Mass data near the edges generate very few hits in a protein database search and are therefore highly specific for protein identification. Mass signals near the low-mass edge indicate either a high probability that the peptide contains one or several cysteine sites, or that the peptide is highly acidic due to the presence of several D and/or E residues or that it is a glycopeptide. Mass data near the high-mass edge indicate a non-polar peptide with a high abundance of the non-polar amino acids leucine, isoleucine and valine. An Internet page is introduced that analyzes the deviation of a peptide mass from the average deltamass value and that supports the characterization of glycopeptides found near the low-mass edge of the mass distribution.
讨论了来自误差≤20 ppm的肽段精确质量数据的分析有用信息。从蛋白质数据库中提取天然肽段的Δ质量（=小数点后的质量值）分布。与随机肽段数据相比，天然数据显示出更高的平均Δ质量值和更窄的质量分布宽度。这种偏差可归因于标准氨基酸的非随机丰度。特别是，位于天然质量分布边缘附近的肽段的精确质量数据包含分析信息。在蛋白质数据库搜索中，边缘附近的质量数据产生的匹配结果很少，因此对蛋白质鉴定具有高度特异性。低质量边缘附近的质量信号表明该肽段很可能含有一个或几个半胱氨酸位点，或者由于存在几个天冬氨酸和/或谷氨酸残基而呈高酸性，或者它是一种糖肽。高质量边缘附近的质量数据表明该肽段是非极性的，含有大量的非极性氨基酸亮氨酸、异亮氨酸和缬氨酸。介绍了一个网页，该网页分析肽质量与平均Δ质量值的偏差，并支持对在质量分布低质量边缘附近发现的糖肽进行表征。
