RCM：上海有机所血清多肽谱学研究取新进展

中国科学院上海有机化学研究所郭寅龙课题组在血清多肽谱学的研究上取得了新进展。他们描述了一种新的N端同位素标记方法（DMPITC）用于分析人血清中差异化表达的低分子量多肽的研究策略。实验材料分别为肾移植无排斥病人和肾移植急性排斥病人。DMPITC配合纳升液相-基质辅助激光解吸附飞行时间质谱（nano LC-offline-MALDI）的检测方法不仅最大限度减少了多肽定量上的误差，也使得差异化表达的标记多肽的序列识别更加容易（轻重标记相差6 Da）。

该项工作由郭寅龙课题组，复旦大学附属中山医院副院长朱同玉课题组，和岛津全球应用技术开发中心赵宁伟合作研究完成，已经被在线发表于国际质谱领域期刊 Rapid Communications in Mass Spectrometry ，此项成果作为血清多肽谱学研究的一种新的技术手段，在生物标志物的发现、疾病早期诊断和个性化治疗等领域将有着广阔的应用前景

DOI: 10.1002/rcm.6369

Analysis of the differentially expressed low molecular weight peptides in human serum via an N-terminal isotope labeling technique combining nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry

Jiapeng Leng1, Dong Zhu2, Duojiao Wu2, Tongyu Zhu2,*, Ningwei Zhao3, Yinlong Guo1,*

RATIONALE
Peptidomics analysis of human serum is challenging due to the low abundance of serum peptides and interference from the complex matrix. This study analyzed the differentially expressed (DE) low molecular weight peptides in human serum integrating a DMPITC-based N-terminal isotope labeling technique with nano-liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (nano-LC/MALDI-MS).

METHODS
The workflow introduced a [d6]-4,6-dimethoxypyrimidine-2-isothiocyanate (DMPITC)-labeled mixture of aliquots from test samples as the internal standard. The spiked [d0]-DMPITC-labeled samples were separated by nano-LC then spotted on the MALDI target. Both quantitative and qualitative studies for serum peptides were achieved based on the isotope-labeled peaks.

RESULTS
The DMPITC labeling technique combined with nano-LC/MALDI-MS not only minimized the errors in peptide quantitation, but also allowed convenient recognition of the labeled peptides due to the 6?Da mass difference. The data showed that the entire research procedure as well as the subsequent data analysis method were effective, reproducible, and sensitive for the analysis of DE serum peptides.

CONCLUSIONS
This study successfully established a research model for DE serum peptides using DMPITC-based N-terminal isotope labeling and nano-LC/MALDI-MS. Application of the DMPITC-based N-terminal labeling technique is expected to provide a promising tool for the investigation of peptides in vivo, especially for the analysis of DE peptides under different biological conditions.