Figure 3.

Aldehdye peptide 3 forms a reversible imine covalent bond with Lys-β71 of HLA-DQ2. (A) Among the DQ2-αI and DQ2-αII aldehyde peptides, peptide 3 had the highest affinity for HLA-DQ2. Moreover, the affinity of peptide 3 for HLA-DQ2 was higher at pH 7 than pH 5. There was no change in the pH 5 affinity of the 20mer peptide (12) upon addition of two aldehyde functional groups (13), although there was a slight improvement at pH 7. (B) HLA-DQ2 dissociation kinetics of aldehyde containing peptide 3 were much slower than the unmodified parent peptide 1 (t_1/2^app (3) = 1400 min.; t_1/2^app (1) = 170 min.).