Rotatory Dispersion and Circular Dichroism of Brain ‘Proteolipid’ Protein1

The proteolipid and its partially delipidated protein from brain tissue have been studied by optical rotatory dispersion and circular dichroism in various solvents. The protein exhibits a helix content of 60–70 per cent in chloroform‐methanol and 2‐chloroethanol and is dextrorotatory in the visible region. In 1,1,1‐trinuoroethanol, a higher helix content of 90 per cent is observed but the protein is laevorotatory. The helix content decreases in water and methanol with a much greater negative specific rotation in methanol. No random coil form has been observed.