Urea-induced denaturation of beta-trypsin: an evidence for a molten globule state.

The denaturation of beta-trypsin induced by urea was investigated by fluorescence and circular dichroism. A transient denatured state was found at 2 M urea in both intrinsic fluorescence spectrum and bis-(8-anilino-1-naphtalene sulfonate) (bis-ANS) binding. In addition, the absence of tertiary contacts and presence of secondary structure for this state, are consistent with an intermediate equilibrium state having features of molten globule.