Denaturation of Proteins: Single or Multiple Step Process?

Abstract

WE have reported the nuclear magnetic resonance (NMR) spectra of eleven proteins covering a wide range of molecular weights in five denaturing solvents¹. With some exceptions the proteins (with disulphide bonds intact) appeared to behave in solution as random coils, devoid of non-covalent interactions. We have thus defined by NMR spectroscopy a particular denatured state (the unfolded state) and the next step is to study the denaturation process brought about by the progressive addition of denaturant to the native protein. At 60 MHz we can examine simultaneously six parameters (proton resonances) of the protein¹. At 220 MHz many more resonances can be observed, because of the much greater resolving power of the spectrometer². Here we direct attention to whether denaturation is a single or multiple step process; a satisfactory answer has often been difficult to obtain in the past³, but it is a prerequisite of any meaningful thermodynamic study of denaturation.