PROBING PROTEIN-STRUCTURE BY SOLVENT PERTURBATION OF NMR-SPECTRA - PHOTOCHEMICALLY INDUCED DYNAMIC NUCLEAR-POLARIZATION AND PARAMAGNETIC PERTURBATION TECHNIQUES APPLIED TO THE STUDY OF THE MOLTEN GLOBULE STATEOF ALPHA-LACTALBUMIN

We have characterized the high-temperature molten globule state of bov ine alpha-lactalbumin by a combined use of photochemically induced dyn amic nuclear polarization and nitroxide surface perturbation. Both tec hniques are extremely well suited to follow the progressive increase o f exposed surfaces in the native state and the appearance of partially or completely unfolded species. Our results suggest that the molten g lobule state obtained at high temperature and pH 7, and the state obta ined at pH 2 are not only thermodynamically but also structurally very similar.