Jayawardene Dhammika, Dass Chhabil
Department of Chemistry, University of Memphis, Memphis, Tennessee 38152, USA.
J Mass Spectrom. 2002 Apr;37(4):389-94. doi: 10.1002/jms.293.
Fragmentation reactions of sodium-cationized enkephalin peptides generated by matrix-assisted laser desorption/ionization were studied using post-source decay (PSD) with a reflectron time-of-flight mass spectrometer. Several matrices and analyte-matrix sample preparation methods were evaluated for high-intensity ion currents that could last for the entire PSD analysis. A triple dried-droplet sample preparation procedure with 2,5-dihydroxybenzoic acid as the matrix was found to yield abundant longer-lasting ion signals of the peptide-Na(+) ion adducts. The principal decay product of these adduct ions is the b(n-1) + Na + OH ion, which provides an unambiguous identification of the C-terminal residue of a peptide. In some peptides, the loss of a second residue from the C-terminus is also observed. No other sequence-specific ions were observed.
利用反射式飞行时间质谱仪的源后衰变（PSD）研究了基质辅助激光解吸/电离产生的钠阳离子化脑啡肽肽段的碎裂反应。评估了几种基质和分析物-基质样品制备方法，以获得可在整个PSD分析过程中持续的高强度离子电流。发现以2,5-二羟基苯甲酸为基质的三重干滴样品制备程序可产生丰富且持久的肽-Na(+)离子加合物离子信号。这些加合物离子的主要衰变产物是b(n-1)+Na+OH离子，它能明确鉴定肽的C端残基。在某些肽中，还观察到从C端丢失第二个残基的情况。未观察到其他序列特异性离子。
