TABLE III.
The DM effect on dissociation of Ii derived peptides is greater for DR3 than for DQ2. Dissociation of peptides from thrombin-treated water soluble molecules (1.6 μM) in the presence of excess competitive high affinity peptides (35 μM) and in the absence or presence of DM (6 μM). Peptide release was determined by MALDI-TOF MS analysis comparing the intensity of the isotopic peaks of added indicator peptides with those of the released peptides. Data from the mean of at least two independent experiments were fitted to a single exponential decay function (Y = As x exp(−ksx)) and values for t1/2 and the coefficient of determination (r2) were calculated.
| Complex | Spontaneous dissociation, t1/2 in hours (r2) | DM-mediated dissociation, t1/2 in hours (r2) | DM-mediated increase in dissociation | ||
|---|---|---|---|---|---|
| DR3-CLIP1 | 61.5 | (0.98) | 0.25 | (0.98) | 246x |
| DQ2-CLIP1 | 144.2 | (0.97) | 9.0 | (0.91) | 16x |
| DQ2-CLIP2 | 141.7 | (0.99) | 5.0 | (0.89) | 28x |
| DQ2-CLIP1 M91A | 13.1 | (0.99) | 0.7 | (0.92) | 19x |
| DQ2-CLIP1 M91P | 93.6 | (0.92) | 8.9 | (0.95) | 11x |
| DQ2-αI | 8.3 | (0.94) | 1.6 | (0.92) | 5x |
| DQ2-γI | 55.2 | (0.96) | 6.9 | (0.96) | 8x |