Poulter L, Ang S G, Williams D H, Cohen P
Biochim Biophys Acta. 1987 Jul 29;929(3):296-301. doi: 10.1016/0167-4889(87)90256-4.
Equimolar mixtures of the phosphorylated and dephosphorylated forms of several peptides have been subjected to fast-atom bombardment mass spectrometry (FABMS), to investigate whether the stoichiometry of phosphorylation can be determined from the relative molecular-ion abundances of the phospho and dephospho derivatives. It is concluded that quantitation can be achieved for peptides with large positive or negative hydrophobicity/hydrophilicity indices (delta F values) where addition of a phosphate group does not alter the distribution of the peptide within the matrix significantly. For peptides with small positive or negative delta F values, phosphopeptides tend to be partially suppressed by their dephosphorylated counterparts. Suppression can be partially or totally overcome by conversion of the peptide to a hydrophobic derivative, and by the selection of an appropriate matrix. Alternatively, addition of a very strong acid, perchloric acid, can even reverse the original suppression effect. This last effect is believed to be due to the increased ionic strength in the matrix, which forces a relatively hydrophilic analyte to the matrix surface; and the ability of such a phosphorylated analyte to form a more stable gas-phase cation.
几种肽的磷酸化和去磷酸化形式的等摩尔混合物已进行快原子轰击质谱分析（FABMS），以研究是否可以从磷酸化和去磷酸化衍生物的相对分子离子丰度确定磷酸化的化学计量。得出的结论是，对于具有大的正或负疏水/亲水性指数（δF值）的肽，可以实现定量分析，在这种情况下，磷酸基团的添加不会显著改变肽在基质中的分布。对于具有小的正或负δF值的肽，磷酸化肽往往会被其去磷酸化对应物部分抑制。通过将肽转化为疏水衍生物以及选择合适的基质，可以部分或完全克服抑制作用。或者，添加非常强的酸高氯酸，甚至可以逆转原来的抑制作用。据信，这最后一种效应是由于基质中离子强度的增加，这迫使相对亲水的分析物到达基质表面；以及这种磷酸化分析物形成更稳定气相阳离子的能力。
