Positional scanning combinatorial peptide libraries (PSCPL) peptides were synthesized using standard solidphase Fmoc chemistry on 2-chlorotrityl chloride resins. Briefly, an equimolar mixture of 19 of the common Fmoc amino acids (excluding cysteine) was prepared for each synthesis and used for coupling in 8 positions, whereas a single type of Fmoc amino acid (including cysteine) was used in one position. This position was changed in each synthesis starting with the N-terminus and ending with the C-terminus. In one synthesis, the amino acid pool was used in all nine positions. X denotes the random incorporation of amino acids from the mixture, whereas the single letter amino acid abbreviation is used to denote identity of the fixed amino acid.