Research Paper リン酸化プロテオミクスの検出感度に関する基礎研究

大坂, 一生

翻訳後修飾タンパク質の検出や構造解析は,医学・薬学の分野において重要である.タンパク質の同定は,そのタンパク質の消化物の質量分析によって行われる.しかし,消化生成物のペプチドはイオン化効率が一律でないため,検出感度が低いペプチドがある.これまでペプチドの検出感度の低下に関する詳細な議論は行われていない.本研究ではペプチドの物性とイオン収量の関係を系統的かつ定量的に評価した.多くの疎水性アミノ酸残基を含むペプチドは正負イオンともにより高い収量を示した.ESIにおいて試料分子のイオンの気化流束はイオン化効率よりもイオン収量に与える影響が大きいことが定量的に示された. : Methods for the proteomic analysis have been established using ESI-MS interfaced with liquid chromatography. If all the peptide ion peaks from a protein digest can be detected in a mass spectrum, accurate identification of the protein can be achieved. However, it is difficult to detect the all tryptic digests because of the different ion yields for each peptide fragment. The ion yields of peptides are strongly dependent upon their physicochemical properties. I have studied the effects of the hydrophobic amino acid Phe residue and the influence of its position in peptides on the positive- and negative-ion yields in ESI. Hydrophobic peptides containing Phe residue(s) were potentially advantageous to the vaporization process from the charged droplet to the gas-phase in ESI, resulting in increased total ion yields in both positive- and negative-ion ESI. The enhancement effect of hydrophobicity on the ion yields was higher than that of basicity and acidity of the peptides in ESI.

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