Figure 1. Substrate-induced stabilization of a mitochondrial ADP/ATP carrier.

(a) As protein molecules in a population unfold due to a gradual rise in temperature (25–90°C), buried cysteine residues become solvent-exposed and accessible to the thiol-specific probe CPM (blue stick representation) that becomes fluorescent upon reaction. (b) Typical unfolding curves of the mitochondrial ADP/ATP carrier of Thermothelomyces thermophila (2 μg) in the absence and presence of 2.5 mM AMP, ADP and ATP, shown in red, blue and green, respectively. (c) The apparent melting temperature (Tm) is the peak in the derivative of the unfolding curve (dF/dT), which is used as an indicator of thermal stability. The apparent melting temperatures reported in the text are from three independent protein purifications.

Figure 1—figure supplement 1. Substrate-induced stabilization of a mitochondrial ADP/ATP carrier.

The substrate concentration-dependency of the apparent melting temperature of purified mitochondrial ADP/ATP carrier. The apparent melting temperature (Tm) was determined from the peak in the derivative of the unfolding curve for different concentrations of AMP, ADP, and ATP in 20 mM HEPES pH 8.0, 100 mM NaCl, 0.1% dodecyl-maltoside, 0.1 mg ml⁻¹ tetraoleoyl cardiolipin. The data are represented by the average and standard deviation of three biological repeats for ADP and ATP, and five biological repeats for AMP.