Our recent experiments on the molten globule state and other protein folding intermediates lead to following conclusions: (i) the molten globule is separated by intramolecular first-order phase transitions from the native and unfolded states and therefore is a specific thermodynamic state of protein molecules; (ii) the novel equilibrium folding intermediate (the 'pre-molten globule' state) exists which can be similar to the 'burst' kinetic intermediate of protein folding; (iii) proteins denature and release their non-polar ligands at moderately low pH and moderately low dielectric constant, i.e. under conditions which may be related to those near membranes.