Methods for the design of libraries of protein variants

A method of designing a collection of protein variants comprising:

• a) inputting a parent protein sequence;
• b) identifying a variable amino acid position in said parent protein sequence;
• c) providing a positional alphabet of m amino acids for said variable position;
• d) choosing a variant pool size n, where m is greater than n;
• e) calculating a suitability score for a plurality of combinations of n amino acids in said alphabet of m amino acids, wherein calculating said suitability score comprises:
• i) a fitness score of each said combination of n amino acids and
• ii) a coverage score calculated by applying a dissimilarity matrix to each said combination of n amino acids;
• and
• f) selecting the combination having the highest suitability score from said plurality of combinations.