Sequencing of the randomized library, of all active clones and of a representative subset of negative clones.

<p>DNA sequencing revealed that only aspartic acid, encoded by the codon GAT, was able to functionally replace cysteine 298. Back mutations to cysteine were also observed. Frequencies (for active clones only) were calculated as the ratio between the number of clones with the specific codon and the total number of screened clones. The results of the sequencing of the whole randomised library and of a representative subset of negative clones are shown.