Figure 3.
Dissociation rate enhancements because of elimination of hydrogen-bonding residues. For each peptide, rate enhancement values were calculated by dividing the dissociation half time of a given peptide from wt class II molecules by the dissociation half time of the same peptide from a given I-Ad mutant (see Table 2). (Upper) The rate enhancement values for His hydrogen-bond loss at pH 5.3 [α-His-68-H− (filled bars) vs. β-His-81-H− (hatched bars)]. (Lower) The rate enhancement values for Asn hydrogen-bond loss at pH 5.3 [α-Asn-69-H− (stippled bars) vs. β-Asn-82-H− (hatched bars)]. Table 2 shows the rate enhancement values displayed by CLIP when tested with each of the variant and wt molecules at pH 7.4.