Figure 4
Composition of NT-TriNuc library before and after expression. (a) Distribution of TriNuc codons in all four positions of the synthetic, ligated and naïve Ser-X-Cys-XXX-Cys tetrapeptide libraries. (b) The distribution of copy numbers in the libraries was calculated using random samples of 60,000 reads from the library. Error bars are standard deviations. For reference, we used random libraries of 60,000 peptides with a uniform ratio of 19 amino acids. (c) Description of a plot showing each peptide in the library as a unique pixel in a specific location. A model 5 × 5 letter plot with 25 × 25 = 625 pixels describes the location of common 4-letter words that contain the letters A, B, C, D and E. (d–f) In the 20:20 plot, the top left quadrant has all peptides of sequence RRxx, top right: RCxx; bottom left: CRxx and bottom right: CCxx. Color indicates the copy number. Each plot contains a random sample of 886,000 reads from deep sequencing for synthetic, ligated and naïve libraries (this number represents ~7 × coverage of theoretical peptide diversity (194 = 1.3 × 105)).
