Identification of four novel types of in vitro protein modifications.
Identification of four novel types of in vitro protein modifications.
复制标题
四种新型体外蛋白质修饰的鉴定。
DOI：
10.1021/pr800456q
复制
发表时间：
2008
影响因子：
4.4
通讯作者：
Zhao,Yingming
中科院分区：
文献类型：
--
作者：
Xing,Gang;Zhang,Junmei;Chen,Yue;Zhao,Yingming
在样品制备过程中引入的蛋白质体外化学修饰会使质谱变得复杂并增加假阳性鉴定的可能性。虽然先前已经描述了几种体外蛋白质修饰，但可能存在其他类型的此类修饰。在这里，我们报告了四种类型的体外蛋白质修饰的发现，通过 HPLC/MS/MS 分析和 PTMap（我们实验室最近开发的一种算法）进行非限制性蛋白质序列比对来识别。这些新颖的体外修饰包括天冬氨酸和谷氨酸的乙基化（+28 Da）、甘油对天冬氨酸和谷氨酸的酯化（+74 Da）、赖氨酸缺失 19 Da 以及半胱氨酸添加 108 Da。我们证实这些修饰发生在体外，而不是在旨在避免可能诱导修饰的条件的体内对照实验中。我们提出了赖氨酸-19 Da 修饰的合理分子机制。因此，我们的研究最终确定了几种新颖的体外蛋白质修饰，提出了避免这些修饰的方法，并强调了由于体外修饰而错误识别肽的可能性。
In vitrochemical modifications in proteins, introduced during sample preparation, can complicate mass spectra and increase the potential for false-positive identifications. While severalin vitroprotein modifications have been described previously, additional types of such modifications may exist. Here, we report discovery of four types ofin vitroprotein modifications, identified by HPLC/MS/MS analysis and nonrestrictive protein sequence alignment by PTMap, an algorithm recently developed in our laboratory. These novelin vitromodifications included ethylation of aspartate and glutamate (+28 Da), esterification of aspartate and glutamate by glycerol (+74 Da), loss of 19 Da from lysine, and addition of 108 Da to cysteine. We confirmed that these modifications occurredin vitroand notin vivoin control experiments designed to avoid conditions likely to induce the modifications. We propose a plausible molecular mechanism for the −19 Da modification of lysine. Our study therefore conclusively identifies several novelin vitroprotein modifications, suggests ways to avoid these modifications, and highlights the possibility of misidentification of peptides because ofin vitromodifications.