Department of Chemistry, Texas A and M University, College Station, Texas 77843, USA.
J Am Soc Mass Spectrom. 2010 Apr;21(4):522-33. doi: 10.1016/j.jasms.2009.12.020. Epub 2010 Jan 11.
Matrix assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) and theoretical calculations [density functional theory (DFT)] were utilized to investigate the influence of cysteine side chain on Cu(+) binding to peptides and how Cu(+) ions competitively interact with cysteine (-SH/SO(3)H) versus arginine. Results from theoretical and experimental (fragmentation reactions) studies on M + Cu and M + 2Cu - H ions suggest that cysteine side chains (-SH) and cysteic acid (-SO(3)H) are important Cu(+) ligands. For example, we show that Cu(+) ions are competitively coordinated to the -SH or SO(3)H groups; however, we also present evidence that the proton of the SH/SO(3)H group is mobile and can be transferred to the arginine guanidine group. For M + 2Cu - H ions, deprotonation of the -SH/SO(3)H group is energetically more favorable than that of the carboxyl group, and the resulting thiolate/sulfonate group plays an important role in the coordination structure of M + 2Cu - H ions, as well as the fragmentation patterns.
基质辅助激光解吸/电离（MALDI）飞行时间（TOF）质谱（MS）和理论计算[密度泛函理论（DFT）]被用于研究半胱氨酸侧链对 Cu(+)与肽结合的影响，以及 Cu(+)离子如何与半胱氨酸（-SH/SO(3)H）与精氨酸竞争相互作用。M + Cu和M + 2Cu - H离子的理论和实验（碎裂反应）研究结果表明，半胱氨酸侧链（-SH）和半胱氨酸磺酸（-SO(3)H）是重要的 Cu(+)配体。例如，我们表明 Cu(+)离子可以竞争性地与 -SH 或 SO(3)H 基团配位；然而，我们也提供了证据表明 SH/SO(3)H 基团的质子是可移动的，可以转移到精氨酸的胍基上。对于M + 2Cu - H离子，-SH/SO(3)H 基团的去质子化比羧基的去质子化更有利，生成的硫醇盐/磺酸盐基团在M + 2Cu - H离子的配位结构以及碎裂模式中起着重要作用。
