A phylogeny of the redesigned copper-binding proteins. The Csp1 template is shown in white in its tetrameric configuration (gray protomers) and the cysteine side chains at the core are depicted in a ball-and-stick representation (PDB:5FJE). The polar side chains introduced in the first-generation design (plr1 model) are shown, yielding a monomeric, positively supercharged protein. Starting from the plr1 sequence, second-generation designs belong to three classes: core-repacked designs where either three (cr3) or six (cr61 and cr62) core cysteine residues were eliminated or negatively supercharged designs (neg1, neg2). Side chains colored yellow are cysteines, blue are positively charged, red are negatively charged, green are polar, and purple are non-polar.
