Divinyl Sulfone as a Postdigestion Modifier for Enhancing the a<sub>1</sub> Ion in MS/MS and Postsource Decay: Potential Applications in Proteomics
作者:Emily S. Boja、Edward A. Sokoloski、Henry M. Fales
DOI:10.1021/ac049774e
日期:2004.7.1
Divinyl sulfone reacts at pH 8−9 with the α-amino groups of N-terminal residues, proline, the ε-amino groups of lysine, and the histidine side chains of peptides. This reaction leads to great enhancement of the abundance of the normally weak or missing “a1” fragment ion in MS/MS analysis defining the N-terminal residue of a peptide in a digest. This provides “one-step Edman-like” information that, together with a fairly accurately determined mass, often enables one to correctly identify a protein or family of proteins. The applicability of this procedure in proteomics was demonstrated with several peptides and tryptic digests of protein mixtures by LC−MS/MS experiments using a QTOF and MALDI-PSD analyses. Advantages of this approach are its simple chemistry, retention of charge multiplicity, and possibly, shortening of database search time. Used with other MS/MS data, it provides higher confidence in the scores and identification of a protein found in peptide mass fingerprinting. Moreover, this approach has an advantage in “de novo” sequencing due to its ability to decipher the first amino acid of a peptide whose information is normally unavailable in MS/MS spectra.
在一项反应中,双乙烯砜在pH 8-9环境下与肽段N端残基、脯氨酸的α-氨基,赖氨酸的ε-氨基和组氨酸侧链发生作用。这种反应大大增强了原本在MS/MS分析中较弱或缺失的“a1”碎片离子的丰度,从而定义了一个蛋白质消化产物中肽链的N端残基。这提供了一种一步法类同于埃德曼降解的序列信息,再加上非常准确的分子量测定,往往能够正确识别一种蛋白质或一组蛋白质。在利用QTOF和MALDI-PSD进行的LC-MS/MS实验中,蛋白质混合物的多种肽链和胰蛋白酶消化产物证明了这一程序在蛋白质组学中的应用性。这一方法的优势在于其简单的化学反应,保留了电荷多样性,并可能缩短了数据库搜索时间。与其他MS/MS数据结合使用,它在肽质量指纹图谱中发现的蛋白质的评分和鉴定方面提供了更高的置信度。此外,由于该方法能够解码通常在MS/MS光谱中无法获得的肽链的第一个氨基酸信息,因此在从头测序方面具有优势。