PHASE RELATIONS IN SYSTEMS COMPRISING BROMINE AND QUATERNARY AND TERNARY ALKYL AMMONIUM BROMIDES OR CHLORIDES

axis will be halved for the structures with the chain running in the same directions. The angular part of the screw operation of the helix was found to depend largely upon radial co-ordinates of the Nbase-Csugar bond: for example, for the pairing 4 and 17, in which Nba8e has a radial co-ordinate of 4.5 A, an angular co-ordinate of about 450 gives a satisfactory structure, as contrasted with the Watson-Crick pairing (5 and 15), which has 6.7 A for the Nbas radius and an angular co-ordinate of 360, the larger radius requiring the shorter angular separation. In the absence of more precise information on the bond lengths, bond angles, and particularly the favored orientations to be expected about the numerous single bonds in the polynucleotide chain, it does not seem appropriate to determine exact atomic co-ordinates, especially since there is latitude of :1 100 or more in the angular separation of the bases. We conclude from this study that polynucleotides may assume two-chain structures other than the one proposed by Watson and Crick.