APC-MCR lacks a cooperative unfolding transition.

<p><b>A</b>, Intrinsic protein fluorescence spectra of APC-MCR measured in 1°C steps from 20°C to 70°C, indicated by a greyscale gradient from black to light grey<b>. B</b>, Comparison of intrinsic tyrosine fluorescence spectra normalised to the maxima. Experiment and colour code as in A. C Temperature dependence of intrinsic tyrosine fluorescence emission of MCR upon stepwise increase of temperature at 340 nm (black) and 304 nm (grey) normalised on maxima of emission.