Buré C, Lelièvre D, Delmas A
Centre de Biophysique Moléculaire, CNRS UPR 4301 affiliated to the University of Orléans and to INSERM, rue Charles Sadron, 45071 Orléans Cedex 02, France.
Rapid Commun Mass Spectrom. 2000;14(23):2158-64. doi: 10.1002/1097-0231(20001215)14:23<2158::AID-RCM147>3.0.CO;2-C.
Synthetic proteins with unusual architecture are obtained through chemoselective ligation, a method based on the condensation of unprotected peptides under mild aqueous conditions. The last step of a new procedure leading to a tri-branched conjugate consists of the chemoselective ligation reaction between an (aminooxy)acetyl peptide and a peptide aldehyde resulting from a first ligation via an oxime bond. In order to optimize the reaction conditions, electrospray ionization mass spectrometry combined with liquid chromatography and tandem mass spectrometry has been used. In addition to the target tri-branched conjugate, two other conjugates were characterized allowing documentation of transoximation reactions in peptide chemistry. A fourth conjugate was identified as a side product appearing after the first ligation. Data obtained by low-energy collision-induced dissociation led to a rapid and reliable identification of impurities observed in the (aminooxy)acetyl peptide despite a previous high performance liquid chromatography (HPLC) purification. This highlights the great reactivity of the aminooxy group towards carbonyl-containing compounds.
具有独特结构的合成蛋白质是通过化学选择性连接获得的，这是一种基于在温和水性条件下未保护肽缩合的方法。一种新方法的最后一步是生成三分支共轭物，该步骤包括（氨氧基）乙酰肽与通过肟键进行首次连接产生的肽醛之间的化学选择性连接反应。为了优化反应条件，已使用了结合液相色谱和串联质谱的电喷雾电离质谱法。除了目标三分支共轭物外，还对另外两种共轭物进行了表征，从而记录了肽化学中的转肟反应。第四种共轭物被鉴定为首次连接后出现的副产物。尽管之前进行了高效液相色谱（HPLC）纯化，但通过低能碰撞诱导解离获得的数据仍能快速可靠地鉴定出（氨氧基）乙酰肽中观察到的杂质。这突出了氨氧基对含羰基化合物的高反应活性。
