The Pasarow Mass Spectrometry Laboratory, NPI-Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, USA.
J Am Soc Mass Spectrom. 2010 May;21(5):868-77. doi: 10.1016/j.jasms.2010.01.026. Epub 2010 Feb 1.
Top-down proteomics characterizes protein primary structures with unprejudiced descriptions of expressed and processed gene products. Gene sequence polymorphisms, protein post-translational modifications, and gene sequence errors can all be identified using top-down proteomics. Saliva offers advantages for proteomic research because of availability and the noninvasiveness of collection and, for these reasons, is being used to search for disease biomarkers. The description of natural protein variants, and intra- and inter-individual polymorphisms, is necessary for a complete description of any proteome, and essential for the discovery of disease biomarkers. Here, we report a striking example of natural protein variants with the discovery by top-down proteomics of two new variants of Peptide P-C. Intact mass measurements, and collisionally activated-, infrared multiphoton-, and electron capture-dissociation, were used for characterization of the form predicted from the gene sequence with an average mass 4371 Da, a form postulated to result from a single nucleotide polymorphism of mass 4372 Da, and another form of mass 4370 Da postulated to arise from a novel protein sequence polymorphism. While the biological significance of such subtle variations in protein structure remains unclear, their importance cannot be assigned without their characterization, as is reported here for one of the major salivary proteins.
自上而下的蛋白质组学以公正的方式描述表达和加工的基因产物，从而对蛋白质的一级结构进行特征描述。基因序列多态性、蛋白质翻译后修饰和基因序列错误都可以使用自上而下的蛋白质组学来识别。由于唾液易于获取且采集无创，因此它为蛋白质组学研究提供了优势，并且正因如此，人们正在利用唾液来寻找疾病生物标志物。要完整描述任何蛋白质组，都需要对天然蛋白质变异体以及个体内和个体间的多态性进行描述，这对于发现疾病生物标志物也是必不可少的。在这里，我们通过自上而下的蛋白质组学发现了肽 P-C 的两个新变体，报告了一个天然蛋白质变异体的惊人例子。我们使用完整质量测量、碰撞激活、红外多光子和电子俘获解离来对从基因序列预测的形式进行特征描述，该形式的平均质量为 4371 Da，另一种形式的质量为 4372 Da，推测是由于质量为 4372 Da 的单核苷酸多态性所致，还有一种形式的质量为 4370 Da，推测是由于新型蛋白质序列多态性所致。虽然这种蛋白质结构的细微变化的生物学意义尚不清楚，但如果不对其进行特征描述，就无法确定其重要性，正如本文对主要唾液蛋白之一的报告。
