Summations of amino acids at N- and C-termini of bLF fragments.

Twenty sheets named for amino acids contain two listings of P’ + P data, one for the N-terminus of each mass spectrometry-determined peptide and one for the C-terminus of that peptide. The 261 individual peptides identified in the 2, 4, and 24 hr VF digests are listed on individual rows. Their N- and C-terminal sequence positions are listed in Column I and Column X, respectively. Excel then extracted the 6 amino acids preceding and following the cut site and placed them in adjacent columns, H and J, and W and Y. Excel then polled these hexapeptides at each position and entered a 1 in the corresponding P1-P6 or P1’-P6’ columns where there was a match to the amino acid named on that sheet. Cells not changed to 1 remained at 0. After all columns were specified as 1 or 0, the columns were summed to give the frequency numbers at the bottom. These summed frequencies were gathered into the “aa Sums” sheet, which represents the total times each amino acid occurred at each P or P’ position, for use in Table 1. (XLSX)