Positive enrichment of C-terminal peptides using oxazolone chemistry and biotinylation.

Selective capture of protein C-termini is still challenging in view of the lower reactivity of the carboxyl group relative to amino groups and difficulties in site-specifically labeling the carboxyl group on the C-terminus rather than that on the side chains of acidic amino acids. For highly efficient purification of C-terminus peptides, a novel positive enrichment approach based on the oxazolone chemistry has been developed in this study. A bifunctional group reagent containing biotin and arginine was incorporated into the C-terminus of protein.

An iTRAQ based quantitative proteomic strategy to explore novel secreted proteins in metastatic hepatocellular carcinoma cell lines.

Secretomics is receiving more and more considerable attention due to the key roles of secreted proteins in cancer. Most of the potential biomarkers for clinical diagnosis and treatment of cancer are secreted proteins. However, the low concentration of secreted proteins and contaminants released from dead cells are a great challenge to secretomic profiling studies.