Main chain units of peptides can join as twofold helical strands which
are parallel to the edges of a regular octahedron which are called
32-chains. These strands can be linked by alpha helical units to form
planes parallel to a regular octahedral face (See rhdopsn.pdf in the
folder "Octahedron" on the site below). It has just been found that
pairs of axially parallel 32-strands can be linked by a single peptide
to form a sheet which is parallel to the faces of a cube. This is
described in the file 32sheet.pdf which has just been placed on the
website--
http://homepage.mac.com/whitby/
where it can be downloaded through the "Files for sharing" link.
