title: Amino and acetamide functional group effects on the ionization and fragmentation of sugar chains in positive-ion mass spectrometry.
abstract: To elucidate the influence of amino (-NH2) and acetamide (-NHCOCH3, -NAc) groups in sugar chains on their ionization and fragmentation, cycloamyloses (cyclodextrins, CyDs) and lacto-oligosaccharide are analyzed by MALDI TOF/TOF and ESI Q-TOF mass spectrometry. CyD derivatives substituted by amino or acetamide groups are ideal analytes to extract the function group effects, which are amino-CyD with one hexosamine (HexNH2) and acetamide-CyD with one N-acetyl hexosamine (HexNAc). Interestingly, the relative ion intensities and isotope-like patterns in their product ion spectra depend on the functional groups and ion forms of sugar chains. Consequently, the results indicate that a proton (H(+)) localizes on the amino group of the amino sugar, and that the proton (H(+)) induces their fragmentation. Sodium cation (Na(+)) attachment is independent from amino group and exerts no influence on their fragmentation patterns in amino group except for mono- and disaccharide fragment ions because there is the possibility of the reducing end effect. In contrast, a sodium cation localizes much more frequently on the acetamide group in acetamide-CyDs because the chemical species with HexNAc are stable. Thus, their ions with HexNAc are abundant. These results are consistent with the fragmentation of lacto-neo-N-tetraose and maltotetraose, suggesting that a sodium cation generally localizes much more frequently on the acetamide group in sugar chains.
authors.affiliation: Suntory Institute for Bioorganic Research, Mishima, Osaka, 618-8503, Japan, yamagaki@sunbor.or.jp.
authors.forename: Tohru
authors.initials: T
authors.lastname: Yamagaki
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Sugahara
authors.forename: Takehiro
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000081:Acetamides / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D000081:Acetamides; D000588:Amines; D009844:Oligosaccharides