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Guanidination of the epsilon-amino group of lysine-terminated tryptic peptides,accomplished with O-methylisourea hydrogen sulfate, converted lysine into homoarginine residues, improving detection in MALDI-MS. Then tryptic peptides were labeled with sulfonic acid groups at the N-termini using 3-sulfopropionic acid NHS-ester chemistry. The derivatives enhanced post-source decay (PSD) fragmentation signals and produced a spectrum containing only y-ions. This facilitated de novo peptide sequencing, so it is an important contribution to unambiguous protein identification in proteome research. This method was successfully applied in nasopharyngeal carcinoma(NPC) proteome study.

The amino acid composition of the dragline fibroin from the spider fibroin of the spider Araneus ventrocosus was analysed and compared with that of the fibroins from different species of spiders. By means of partial acid hydrolysis and high performance liquid chromatography, several peptide fragments of the dragline fibroin were purified. The amino acid sequence analysis showed the sequences of these peptides to be different from that of the fibroin from the spider Nephila clavipes except for one common fragment with the sequence of GYGPG.