Case Study 1
The NNK library is a classic degenerate mutation library. The NNK degenerate primers used contain 32 (4x4x2) codon combinations (N= A/C/G/T, K= G/T), covering all 20 amino acids with the ability to saturate amino acids at any site.
Fig.1 The proportion of each codon contained in the five NNK sites in the NNK library
Case Study 2
Trimer libraries can be used for site saturation mutation to distribute 20 amino acids in equal proportion, further reducing codon redundancy and removing termination codons in the library.
Fig.2 Trimer libraries are also a saturated mutation library with equal distribution of each amino acid
Case Study 3
Trimer libraries can also customize each site to be composed of different ratios of amino acids. Among the four Trimer sites, for example, the X1 Trimer site is A (80%) : G (3%) : R (3%) : S (3%): T (8%) : V (3%)
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Fig.3 Types and proportions of custom amino acids
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Fig.4 Ratio between actual and theoretical proportion of each amino acid
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