Effect of sodium dodecyl sulfate, acid, alkali, urea and guanidine hydrochloride on the circular dichroism of alpha-globulin of Sesamum indicum L.

The circular dichroic spectra of a-globulin have been obtained under various
solution conditions of sodium dodecyl sulfate, acid, alkali, urea and guanidine
hydrochloride. The protein in phosphate buffer pH 7.4, 0 . 2 , h~a s about 25% bstructure
and 5% a-helix, the rest being aperiodic or irregular structure. Sodium
dodecyl sulfate induced more a-helical structure in the protein. The protein had
nearly 20% a-helix at 1 x lo-= M SDS. At extreme acid or alkaline pH, the
protein had no a-helix with Pstructure decreasing with further extremes of pH.
The protein is represented by 100% aperiodic structure in 6.6 m urea and in 6.0 m guanidine hydrochloride solutions. The above results are discussed in view
of some of the earlier results with regard to the association-dissociation and
denaturation behavior of a-globulin under various solution conditions.