Amino acid diversity encoded in second generation library.

CDR’ refers to a degenerate codon with the following nucleotide frequencies: 20% A, 15% C, 25% G, and 40% T at site 1, 50% A, 25% C, 15% G, and 10% T at site 2, and 0% A, 45% C, 10% G, and 45% T at site 3. Loop length diversity was afforded at mid-loop positions by inserting CDR’ diversity sites between sites P25-V29 and G79-S85 of the BC and FG loop, respectively, as denoted by subscripts within table. Length diversity at the DE loop occurred between S53-S55, consisting of either wild-type length or the exclusion of K54.