Mann M, Wilm M
Protein & Peptide Group, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
Anal Chem. 1994 Dec 15;66(24):4390-9. doi: 10.1021/ac00096a002.
We demonstrate a new approach to the identification of mass spectrometrically fragmented peptides. A fragmentation spectrum usually contains a short, easily identifiable series of sequence ions, which yields a partial sequence. This partial sequence divides the peptide into three parts-regions 1, 2, and 3-characterized by the added mass m1 of region 1, the partial sequence of region 2, and the added mass m3 of region 3. We call the construct, m1 partial sequence m3, a "peptide sequence tag" and show that it is a highly specific identifier of the peptide. An algorithm developed here that uses the sequence tag to find the peptide in a sequence database is up to 1 million-fold more discriminating than the partial sequence information alone. Peptides can be identified even in the presence of an unknown posttranslational modification or an amino acid substitution between an entry in the sequence database and the measured peptide. These concepts are demonstrated with model and practical examples of electrospray mass spectrometry/mass spectrometry of tryptic peptides. Just two to three amino acid residues derived by fragmentation are enough to identify these peptides. In peptide mapping applications, even less information is necessary.
我们展示了一种鉴定经质谱裂解的肽段的新方法。裂解谱通常包含一系列短的、易于识别的序列离子，由此可得到部分序列。该部分序列将肽段分为三个部分——区域1、区域2和区域3，其特征分别为区域1的附加质量m1、区域2的部分序列以及区域3的附加质量m3。我们将这种结构m1部分序列m3称为“肽序列标签”，并表明它是该肽段的高度特异性标识符。此处开发的一种算法利用该序列标签在序列数据库中查找肽段，其鉴别能力比仅使用部分序列信息时高出多达100万倍。即使存在未知的翻译后修饰或序列数据库中的条目与所测肽段之间存在氨基酸替换，也能够鉴定出肽段。通过胰蛋白酶肽段的电喷雾质谱/质谱的模型和实际示例对这些概念进行了演示。仅通过裂解得到的两到三个氨基酸残基就足以鉴定这些肽段。在肽图分析应用中，所需信息甚至更少。
