FIGURE 4.

Previously designed variant identified in homologue and enhanced by core substitution. See supplemental Table S2 for a complete list of the mutations made for every variant protein. a, cleavage profiles for the I-AchIP-based variants K24N/T29K and K24N/L28V/T29K on position −8 confirm previously predicted computational mutations for −8G (19). Introducing the L28V core substitution increased activity slightly at three of the four possible bases at this position. b, the computationally predicted model for these amino acid mutations (19). Asn-24 forms a hydrogen bond with −8C, whereas Lys-29 is able to form two hydrogen bonds with −8G.