Tryptic mapping peptide products

Figure 3. Identification of a protein by peptide mass fingerprinting. The protein constituents of pig saiiva were separated by SD-PAGE and a protein band was digested with trypsin. The resuitant tryptic peptides were mass-measured using MALDI-ToF mass spectrometry. The peptides in the mass spectrum were either derived from trypsin self-digestion (T) or were derived from the protein in the gel- Database searching with the masses of these peptides led to an unequivocal identification of the protein as SAL (salivary lipocalin). The inset map shows the theoretical tryptic digestion map of this protein, and underneath are the peptides that were observed. In many instances, smaller peptides were visible as partial digestion products.

A compaxison of the tryptic peptide maps of VPg and this small molecular weight in vitro translation product should enable us to decide whether YPg is coded for by the region of the genome to the 5 side of the poly(c) tract. 

In their initial experiments, Sangar et al. (28) found foxir primary products in PMDV-infected BHK 21 cells but a re-assessment was made after tryptic peptide analysis of these products had shown that two of them, P56 and PI00, gave similar maps. The second series of experiments (29) showed that, as with other picomavimises, only three primary products 5 - P188, P52, PI 00 - 5 are present. The polypeptide.P56 is apparently part of PI00. 

As indicated above, three primary products are found in BHK 21 cells infected with PMiy. The tryptic peptide maps of P88 and P52 of the three strains A61 and A Bage show clearly that there are... 

BOBOS, P. and PLOBRBE, J.Y. Precursor-product relationship of encephalomyocarditis virus-specific polypeptides. Comparisons by tryptic peptide mapping. Eur. J. Biochem. (1973), 39. 

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