Cedars-Sinai Medical Center, Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Los Angeles, CA, USA.
Chair of Pharmacology, Jagiellonian University Medical College, Institute of Pharmacology, Krakow, Poland.
Methods Mol Biol. 2022;2420:107-126. doi: 10.1007/978-1-0716-1936-0_9.
Citrullination, the Ca-driven enzymatic conversion of arginine residues to citrulline, is a posttranslational modification, implicated in several physiological and pathological processes. Several methods to detect citrullinated proteins have been developed, including color development reagent, fluorescence, phenylglyoxal, and antibody-based methods. These methods yet suffer from limitations in sensitivity, specificity, or citrullinated site determination. Mass spectrometry (MS)-based proteomic analysis has emerged as a promising method to resolve these problems. However, due to low abundance of citrullinated proteins and similar MS features to deamidation of asparagine and glutamine, confident identification of citrullinated proteome is challenging. Here, we present a systematic approach to identify a compendium of steps to enhance the number of detected citrullinated residue and implement diagnostic MS feature that allow the confidence of MS-based identifications. Our method is based on the concept of generation of hyper-citrullinated library with high-pH reversed-phase peptide fractionation that allows to enrich in low abundance citrullinated peptides and amplify the effect of charge loss upon citrullination. Application of our approach to complex global citrullino-proteome datasets demonstrates the confident assessment of citrullinated peptides, thereby enhancing the size and functional interpretation of citrullinated proteomes.
瓜氨酸化,即 Ca2+ 驱动的精氨酸残基转化为瓜氨酸的酶促转换,是一种翻译后修饰,涉及多种生理和病理过程。已经开发了几种检测瓜氨酸化蛋白的方法,包括显色试剂、荧光、苯乙醛酸和基于抗体的方法。这些方法在灵敏度、特异性或瓜氨酸化位点确定方面仍存在局限性。基于质谱(MS)的蛋白质组学分析已成为解决这些问题的有前途的方法。然而,由于瓜氨酸化蛋白的丰度低,并且与天冬酰胺和谷氨酰胺的脱酰胺作用具有相似的 MS 特征,因此,对瓜氨酸化蛋白质组的可靠鉴定具有挑战性。在这里,我们提出了一种系统的方法来确定一系列步骤,以增加检测到的瓜氨酸化残基的数量,并实施诊断 MS 特征,从而提高基于 MS 的鉴定的可信度。我们的方法基于高 pH 反相肽分级产生超瓜氨酸化文库的概念,该文库可富集低丰度的瓜氨酸化肽,并放大瓜氨酸化引起的电荷损失效应。将我们的方法应用于复杂的全局瓜氨酸化蛋白质组数据集,证明了瓜氨酸化肽的可靠评估,从而增强了瓜氨酸化蛋白质组的大小和功能解释。