Jackson Shelley N, Moyer Susanne C, Woods Amina S
National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA.
J Am Soc Mass Spectrom. 2008 Oct;19(10):1535-41. doi: 10.1016/j.jasms.2008.06.023. Epub 2008 Jul 3.
Electrospray mass spectrometry (ESI-MS) has become the tool of choice for the study of noncovalent complexes. Our previous work has highlighted the role of phosphorylated amino acid residues in the formation of noncovalent complexes through electrostatic interaction with arginine residues' guanidinium groups. In this study, we employ tandem mass spectrometry to investigate the gas-phase stability and dissociation pathways of these noncovalent complexes. The only difference in the three phosphopeptides tested is the nature of the phosphorylated amino acid residue. In addition the absence of acidic residues and an amidated carboxyl terminus insured that the only negative charge came from the phosphate, which allowed for the comparison of the noncovalent bond between arginine residues and each of the different phosphorylated residues. Dissociation curves were generated by plotting noncovalent complex ion intensities as a function of the nominal energy given to the noncovalent complex ion before entering the collision cell. These results showed that noncovalent complexes formed with phosphorylated tyrosine were the most stable, followed by serine and threonine, which had similar stability.
电喷雾质谱法（ESI-MS）已成为研究非共价复合物的首选工具。我们之前的工作强调了磷酸化氨基酸残基通过与精氨酸残基的胍基进行静电相互作用在非共价复合物形成中的作用。在本研究中，我们采用串联质谱法来研究这些非共价复合物的气相稳定性和解离途径。所测试的三种磷酸肽之间的唯一差异在于磷酸化氨基酸残基的性质。此外，不存在酸性残基和酰胺化的羧基末端确保了唯一的负电荷来自磷酸基团，这使得能够比较精氨酸残基与每个不同磷酸化残基之间的非共价键。通过绘制非共价复合离子强度与在进入碰撞池之前给予非共价复合离子的标称能量的函数关系来生成解离曲线。这些结果表明，与磷酸化酪氨酸形成的非共价复合物最稳定，其次是丝氨酸和苏氨酸，它们具有相似的稳定性。
