On Tue, 13 Feb 1996, William Pitt wrote:
>
> Question: is it possible that someone will ever design a quadruple (or
> more) stranded DNA structure?
>
Wouldn't that be the Holliday Junction?
Occurs naturally, but no structure has yet been done.
However, see pdb codes 196d and 1hjr
structures
http://www.cryst.bbk.ac.uk/PDB/pdb196d.pdb and
http://www.cryst.bbk.ac.uk/PDB/pdb1hjr.pdb
and the bibliographical references
gopher://pdb.pdb.bnl.gov:70/00/PDB/Entries/.1hjr/1hjr.biblio and
gopher://pdb.pdb.bnl.gov:70/00/PDB/Entries/.196d/196d.biblio
I suspect one, two, and three and four stranded structures need to be
allowed for in your designs, at least.
Oh, and don't forget single and double-stranded circular loops, with
varying degrees of supercoiling in the latter case.
Rgds.,
Alan Mills at Venus Internet Ltd, 24 Denmark Street, London WC2H 8NJ, UK
email:alan@venus.co.uk web:http://www.venus.co.uk
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