A conformation change induced in the basic encephalitogen by lipids

Abstract

Using ORD/CD we have studied the conformation of the basic encephalitogenic protein isolated from normal human myelin. Using the curve fitting method we have found this protein to be essentially random. When sodium dodecyl sulphate was added to a solution of the protein the random curve obtained by ORD was altered to an α-helical type. Addition of sodium dodecyl sulphate, sodium oleate or triphosphoinostide to the protein, all had the effect of changing the CD curve from random to α-helical type. The most effective agent was sodium dodecyl sulphate since it produced the largest rotation. Positively charged lipids, cetyltrimethylammonium bromide and lysolecithin did not affect the random CD curve at pH 2.0. However, at pH 5.0 where lysolecithin is a zwitterion, the CD curve appeared to be α-helical.