First Observation of the Molten Globule State of a Single Homopolymer Chain.
In a recent laser light-scattering study on the “globule-to-coil” transition (melting) of a single poly( Nisopropylacrylamide) (PNIPAM) linear chain in water (the solution is in the stable one-phase regio all temperatures), we observed that at the initial melting stage the ratio of the hydrodynamic radi the radius of gyration underwent an unexpected maximum s,1.61d which is even higher thans5y3d1y2 predicted for a rigid and uniform globule, indicating a molten globule. This finding suggests that as with a protein molecule the melting of a homopolymer globule is not an all-or-none process an molten state is a general phenomenon for macromolecules in solution. [S0031-9007(96)01345-