Natural polypeptides in left-handed helical conformation. A circular dichroism study of the linker histones' C-terminal fragments and beta-endorphin.

Circular dichroism has been used to investigate the histone H1 and H5 C-terminal fragments and beta-endorphin conformation. It has been shown that in aqueous solution these polypeptides preferably adopt the left-handed helical conformation of the poly-L-proline II type. A break in the linear temperature dependence of the CD value was found in the temperature interval between 50 and 55 degrees C. It was proposed to be due to non-cooperative disordering of the conformation caused by the destruction of the hydration shell.