The Ff filamentous viruses (fd, M13, f1) are important models for memb
rane protein assembly and are used extensively as cloning vectors and
vehicles for peptide display The thread-like virion (approximate to 6
nm x 880 nm) comprises a single-stranded DNA genome sheathed by approx
imate to 2700 copies of a 50-residue alpha-helical subunit (pVIII). Th
e average inclination of pVIII subunits from the virion axis has been
determined experimentally by polarized Raman microspectroscopy of orie
nted fd fibers, using the amide I Raman tensors obtained from a peptid
e single crystal. It is found that the average tilt angle, theta, betw
een the pVIII alpha-helix and the virion axis falls within the range 1
3 < theta < 20 degrees. (C) 1996 Academic Press Limited