Brame Cynthia J, Moran Michael F, McBroom-Cerajewski Linda D B
MDS Proteomics Inc, 251 Attwell Dr, Toronto, Ontario, M9W 7H4, Canada.
Rapid Commun Mass Spectrom. 2004;18(8):877-81. doi: 10.1002/rcm.1421.
The arginine methylation of proteins is involved in several important cellular activities, most notably transcriptional control. Arginine dimethylation can take two distinct forms, symmetric and asymmetric, catalyzed by different classes of enzymes. To establish a method for the mass spectrometric identification and characterization of this post-translational modification, we analyzed synthetic peptides with symmetrically or asymmetrically methylated arginine residues by electrospray ionization tandem mass spectrometry. We observed abundant characteristic ions at M+nH-31 and M+nH-70 in spectra of symmetrically methylated peptides and at M+nH-45 in spectra of asymmetrically methylated peptides. We speculate these ions arise from neutral loss of monomethylamine, dimethylcarbodiimide, and dimethylamine, respectively. These characteristic ions allowed the rapid identification of a symmetrically arginine-dimethylated peptide from myelin basic protein and a symmetrically arginine-dimethylated peptide from SmD3 co-immunoprecipitated with the methyltransferase-associated protein pICln, suggesting that this method may provide a rapid means to screen for and characterize dimethylarginine sites.
蛋白质的精氨酸甲基化参与多种重要的细胞活动，其中最显著的是转录调控。精氨酸二甲基化可呈现两种不同形式，即对称型和非对称型，由不同类别的酶催化。为建立一种用于质谱鉴定和表征这种翻译后修饰的方法，我们通过电喷雾电离串联质谱分析了带有对称或非对称甲基化精氨酸残基的合成肽。我们在对称甲基化肽的谱图中观察到大量特征离子M + nH - 31和M + nH - 70，在非对称甲基化肽的谱图中观察到特征离子M + nH - 45。我们推测这些离子分别源于一甲胺、二甲基碳二亚胺和二甲胺的中性丢失。这些特征离子使得能够快速鉴定出髓鞘碱性蛋白中的对称精氨酸二甲基化肽以及与甲基转移酶相关蛋白pICln共免疫沉淀的SmD3中的对称精氨酸二甲基化肽，这表明该方法可能为筛选和表征二甲基精氨酸位点提供一种快速手段。
