Estimation of the secondary structure of protein A from S. aureus by CD-spectroscopy.

The secondary structure of protein A(SpA) was estimated to 31% alpha-helix, 13% beta-structure and 56% random coil by CD-spectroscopy, which is close to the sum of the secondary structures of the SpA fragments. This supports that the SpA molecule is composed N-terminally of four Fc-binding units each consisting of two antiparallel alpha-helices interconnected by random coil segments and C-terminally of an region mainly in random coil.