Lysine peptides separation

Repeated addition of MDC to Q11 did occur, but the dominant product was Q11 with a single MDC. The fraction of Qll with higher numbers of attached MDC decreased for increasing MDC number. Separately, a lysine peptide that contained the bioactive RGD [73] sequence ( -dansyl-GLKGGRGDS-Am) was successfully TGase crosslinked with self-assembled Qll five distinct Qll-dansyl RGD were detected by mass spectrometry. 

The proteolytic digestion of j6-lactoglobulin was carried out with trypsin which, as indicated in Table 5.4 above, is expected to cleave the polypeptide backbone at the carboxy-terminus side of lysine (K) and arginine (R). On this basis, and from the known sequence of the protein, nineteen peptide fragments would be expected, as shown in Table 5.7. Only 13 components were detected after HPLC separation and, of these, ten were chosen for further study, as shown in Table 5.8. 

Figure 19.8 To study the conjugation of peptides to carriers using different levels of EDC, tyrosyl-lysine was conjugated to BSA and separated after the reaction by chromatography on a Sephadex G-25 column. As the EDC level was increased in the reaction, more peptide reacted and the peptide peak (the second peak) was depleted. The absorbance of the carrier peak (the first one) increases as more peptide is conjugated.

Two-dimensional electrophoresis [86] is a well established technique for the separation of intact proteins. In the first dimension the proteins are separated based on their isolectric point while the second dimension separates them based on their size. The presence on the gel of the proteins is revealed by Coomassie blue or silver staining. Under favorable conditions several thousand spots can be differentiated. The gel is digitized and computer-assisted analysis of the protein spot is performed. The spots of interest are excised either manually or automatically and then digested with trypsin. Trypsin cleaves proteins at the C-terminal side of lysine and arginine. In general one spot represents one protein and the peptides are analyzed by MALDI-TOF to obtain a peptide mass fingerprint. A peptide mass fingerprint involves the determination of the masses of all pep-... 

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