MALDI-QIT-TOFMSを用いた糖タンパク質の新規構造解析手法:リボヌクレアーゼBへの適用

抄録

Mass spectrometry (MS) is becoming an indispensable analytical tool for glycoproteomics, that is, for the analysis of glycan and protein structures of glycoproteins. While a simple and rapid MS method which can minimize troublesome procedures for sample preparation is desired, a single mass spectrometer to meet this demand has not been realized to date. We report here a procedure for the structure analysis of Ribonuclease B (RNase B) using the MS and MSⁿ analyses of protonated ions ([M+H]⁺) and sodium-adducted ions ([M+Na]⁺) by a single MALDI-QIT-TOFMS. Five peaks were identified as a glycopeptide in mass spectra with 2,5-dihydroxybenzoic acid (DHBA) as a matrix for RNase B digests by Lysyl endopeptidase (Lys C) without desalting. All of the five [M+H]⁺ peaks were accompanied by [M+Na]⁺ peaks. The same fragment peaks were observed in low mass area of all MS/MS spectrum for each [M+H]⁺ or [M+Na]⁺ species. MSⁿ analyses using [M+H]⁺ as a precursor ion provided the information of peptide sequence and glycosylation site, while fragments from [M+Na]⁺ showed oligosaccharide sequence. Finally, this technique using [M+H]⁺ and [M+Na]⁺ with MALDI-QIT-TOFMS realized an easy and high-throughput implementation of glycoprotein structure analyses.