pH响应型巯基肽特异富集材料壳聚糖衍生物的合成优化及应用

How to realize efficient and specific enrichment of cysteine containing peptides from tryptic digests of complex protein mixtures has always been a challenge. Firstly, this paper describes the development of chitosan derivatives (O-CMC-PBS-5MP) with the ability of self-assembly and capture / release of cysteine containing peptides based on pH responsive, and then the synthesized enrichment material was characterized by infrared spectroscopy, full wavelength scanning analysis and 13C-NMR. The effect of chitosan molecular weight on the stability of covalent 5MP group treated with simulated pH condition was expolred. Furthermore, the capture ability specificity of O-CMC-PBS-5MP for cysteine containing peptides was tested using GC-7 containing cysteine, as well as, the capture specificity of O-CMC-PBS-5MP for cysteine containing peptides was done using GC7 and 8 peptide without cysteine as the interference in high ratio. Finally, the selected cysteine containing peptides of GC7 from the mixture of GC7 and 8 peptide in high ratio was used directly for LC-MS and MALDI-TOF-MS analysis. The results of these studies showed that O-CMC-PBS-5MP is precipitated under acidic conditions (pH<3) and the precipitation was re-dissolved under alkaline conditions (pH ≥ 10.0). The 5MP group of O-CMC-PBS-5MP with 400 kDa chitons was the most stable in the whole simulated selection process, which capture rate of O-CMC-PBS-5MP for GC-7 could reach 90% and the release rate could reach approximately 54%, and the specific enrichment rate of mercaptopeptide GC-7 could reach 50%. The selected GC7, which will not need further treatment, could be directly applied for the LC - MS and MALDI - MS analysis.