Three states of the pFh-fragment (Hinge region) from human myeloma IgG3 Kuc with native-like secondary structure.

The structure of the pFh-fragment (hinge region) from human myeloma IgG3 Kuc (the third subclass immunoglobulin) was studied by hydrodynamic methods in the pH range from 3.0 to 8.0. The pFh-fragment was found to occur in three states, each with a high content of the secondary structure: a rod-like state at pH < or = 4.0, a "molten globule" state at pH 4.2-5.5, and the native state at pH 7. 5-8.0.