“…Thus, the combinatorial approach, which consists of generating random variants coupled to a screening for stability, and methods based on sequence/structure homology have proved to be some of the most successful strategies to improve the stability of numerous proteins (for reviews, see (Bommarius et al, 2006;Romero and Arnold, 2009) Affitins are artificial affinity proteins that we have developed which are derived from extremophilic proteins from the "7 kDa DNA-binding" family found in Archaea, such as Sac7d (Béhar et al, 2013;Buddelmeijer et al, 2009;Krehenbrink et al, 2008;Mouratou et al, 2007). Sac7d is a hyperthermostable protein (T m = 90.4 • C) (Edmondson and Shriver, 2001;McCrary et al, 1996;Mouratou et al, 2007) and is chemically resistant from pH 0 up to pH 12 (Béhar et al, 2013). Binders with high pH and thermal stabilities have been obtained by coupling the generation of combinatorial libraries of Sac7d variants corresponding to the randomization of 10-14 residues of the -sheet surface originally involved in the binding of DNA and selections against different targets.…”