How does urea really denature myoglobin?

The experimental data for denaturation of myoglobin in aqueous solutions by urea for concentrations ranging from 0.1 M to 15 M using quartz crystal microbalance (QCM), circular dichroism (CD) and dilational rheology are examined with respect to a 'structure-breaking effect' of urea on the aqueous phase. Our study shows that any proposed denaturation mechanism of large biomolecules requires very high concentrations of urea and the association of urea with protein-water system is based on enhancement of hydrophobic interactions.