The control of structure on the nanoscale relies on intermolecular interactions whose specificity and geometry can be treated on a predictive basis. DNA appears to be a tractable construction medium for this purpose. Stable DNA branched junction molecules can be formed after the sequences are selected by a sequence-symmetry minimization procedure. By this means, I have constructed the DNA branched junctions that contain either five arms or six arms surrounding a branch point. I have characterized these junctions by means of gel electrophoresis and enzymatic analysis. These junctions are not as stable as junctions containing three or four arms; longer arms are needed for the stabilization of five and six arm junctions.; Branched DNA molecules can be assembled into structures whose helix axes form multiply-connected objects and networks. The ability to construct five-arm and six-arm junctions vastly increases the number of structures and networks that can be built from branched DNA components.; DNA polyhedra, such as a DNA molecule whose helix axes have the connectivity of a cube, is a promising substrate for the attachment of other macromolecules. This kind of attachment will permit juxtaposition of molecules not found together in nature. I have attached a single molecule of alkaline phosphatase to the cube-like DNA molecule using a covalent tether. This is the first report of a DNA polyhedron linked covalently to another macromolecule.
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