The document CstrndsH2PO4.pdf shows how each of the four C-atom
quintuplets derived from an L-triplet forms edgially axised strands
with H2PO4-groups. The inter-strand relationship of the H2PO4-groups
is identical in each of the strands formed by the four quintuplets.
Each of the quintuplets is a candidate for the backbone of D-ribose.
Each of the strands is a candidate for the sugar-phosphate backbone of
RNA and DNA.
The file can be downloaded from the "Files for sharing" page of the
website
http://homepage.mac.com/whitby/
