Pressure-Temperature Analysis of the Stability of the CTL9 Domain Reveals Hidden Intermediates (Biophysical Journal)

The observation of two-state unfolding for many small, single domain proteins by denaturants has led to speculation that protein sequences may have evolved to limit the population of partially folded states that could be detrimental to fitness. How such strong cooperativity arises from a multitude of individual interactions is not well understood. Here we investigate the stability and folding cooperativity of the C-terminal domain of the ribosomal protein L9 in the pressure-temperature plane using site-specific NMR.