FIG 2.

Thermal stability of wild-type HIV-1 protease (PR^WT) and lysozyme in the presence and absence of each compound using differential scanning fluorimetry (DSF). The relative fluorescence intensity was plotted at each temperature. Melting temperature (T_m) values were calculated from the top of the peak in the derivative plot. (A) Melting curves of PR^WT in the presence and absence of selected FDA-approved PIs. Thermal stability curves with all the compounds shifted to higher temperatures than in the absence of each compound with T_m values ranging from 75.42 (amprenavir [APV]) to 83.08°C (tipranavir [TPV]), with a ΔT_m value of 19.24°C to 26.90°C. (B) Melting curves of PR^WT in the presence and absence of GRL-057-14, GRL-058-14, and GRL-059-14. The curve of DRV is shown as a reference. All three compounds significantly shifted the thermal stability curves to higher temperatures than in the absence of each compound. Their T_m values were much higher than those of all the FDA-approved PIs tested (A). (C) Melting curves of lysozyme in the presence and absence of GRL-057-14, GRL-058-14, GRL-059-14, and DRV. None of the PIs examined affected the thermal stability curves, indicating that all the PIs examined were highly specific to PR^WT and had no significant interactions with lysozyme.