FIGURE 7.

Change in T_m as a function of percent bleach for rhodopsin in native disk membranes (squares), 16% dimeric rhodopsin in cross-linked disk membranes (triangles), and 34% dimeric rhodopsin in cross-linked disk membranes (circles). The change in T_m was calculated relative to the average T_m of at least three scans of unbleached disk membranes (T_mavg = 72.5 ± 0.5, 71.8 ± 0.1, and 72.9 ± 0.3, respectively). Differences in the T_mavg represent variability between disk membrane and cross-linking preparations. The T_m of each respective endotherm was recorded from excess heat capacity curves of ∼0–60% bleached disk membranes at a 1.5°/min scan rate. Linear regression analysis produced slopes that significantly deviated from zero for the cross-linked disk membranes (>99.9% confidence level).