Two base-pair repeat in the C-form of poly d(AG).poly d(CT), symmetric model
in which the two strands are conformational identical. Successive repeating
units can be generated by adding multiples of 80 degrees to phi and the same
multiple of 0.6467 nm to z.  [ignoring H atoms]

            --------------------------------------------------------------------
             Group      Atom      x(nm)     y(nm)     z(nm)     r(nm)   phi(deg)
            --------------------------------------------------------------------
            PHOSPHATE   P       -0.5668    0.6528    0.4477    0.8645    130.97
                        O1      -0.6550    0.5614    0.3717    0.8627    139.40
                        O2      -0.6321    0.7712    0.5077    0.9972    129.34
                        O3      -0.4897    0.5706    0.5614    0.7520    130.64
                        O5      -0.4453    0.6998    0.3548    0.8294    122.47

            SUGAR       C1      -0.1642    0.5037    0.3269    0.5298    108.06
                        C2      -0.1327    0.6104    0.2254    0.6247    102.26
                        C3      -0.1118    0.7334    0.3137    0.7419     98.67
                        C4      -0.2140    0.7126    0.4255    0.7441    106.72
                        C5      -0.3451    0.7873    0.4099    0.8596    113.67
                        O4      -0.2412    0.5696    0.4290    0.6186    112.95

            ADENINE     N1      -0.1592    0.0108    0.1845    0.1596    176.11
                        C2      -0.0643    0.0918    0.2312    0.1121    125.02
                        N3      -0.0730    0.2181    0.2667    0.2300    108.49
                        C4      -0.1987    0.2640    0.2502    0.3305    126.97
                        C5      -0.3059    0.1934    0.2036    0.3619    147.69
                        C6      -0.2839    0.0592    0.1690    0.2900    168.23
                        N6      -0.3798   -0.0218    0.1219    0.3805   -176.71
                        N7      -0.4191    0.2736    0.2003    0.5005    146.86
                        C8      -0.3775    0.3883    0.2443    0.5416    134.19
                        N9      -0.2449    0.3903    0.2766    0.4608    122.11

       ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            PHOSPHATE   P        0.1346   -0.8182   -0.3030    0.8292    -80.66
                        O1       0.0746   -0.9360   -0.2363    0.9389    -85.44
                        O2       0.2393   -0.8468   -0.4035    0.8800    -74.22
                        O3       0.0191   -0.7296   -0.3695    0.7298    -88.50
                        O5       0.1920   -0.7175   -0.1927    0.7428    -75.02

            SUGAR       C1       0.2904   -0.4627    0.0658    0.5079    -65.66
                        C2       0.2383   -0.6093    0.0962    0.6543    -68.64
                        C3       0.3652   -0.6324    0.0142    0.7303    -59.99
                        C4       0.3417   -0.5461   -0.1098    0.6442    -57.96
                        C5       0.2894   -0.6190   -0.2320    0.6833    -64.94
                        O4       0.2450   -0.4446   -0.0703    0.5076    -61.14

            THYMINE     N1       0.0659   -0.4256    0.0811    0.4307    -81.20
                        C2       0.0378   -0.2937    0.1071    0.2961    -82.66
                        O2       0.1243   -0.2084    0.1178    0.2427    -59.19
                        N3      -0.0962   -0.2631    0.1207    0.2801   -110.08
                        C4      -0.2018   -0.3513    0.1105    0.4051   -119.87
                        O4      -0.3178   -0.3121    0.1246    0.4454   -135.52
                        C5      -0.1623   -0.4875    0.0830    0.5138   -108.42
                        ME      -0.2711   -0.5900    0.0705    0.6493   -114.68
                        C6      -0.0328   -0.5200    0.0694    0.5210    -93.60

       ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            PHOSPHATE   P        0.1343    0.8182    0.3030    0.8291     80.68
                        O1       0.0743    0.9359    0.2363    0.9389     85.46
                        O2       0.2390    0.8468    0.4035    0.8799     74.24
                        O3       0.0189    0.7296    0.3695    0.7298     88.52
                        O5       0.1918    0.7176    0.1927    0.7427     75.04

            SUGAR       C1       0.2902    0.4627   -0.0658    0.5078     65.67
                        C2       0.2381    0.6094   -0.0961    0.6542     68.66
                        C3       0.3650    0.6325   -0.0142    0.7303     60.01
                        C4       0.3415    0.5462    0.1099    0.6442     57.98
                        C5       0.2892    0.6191    0.2321    0.6833     64.96
                        O4       0.2449    0.4446    0.0704    0.5076     61.16

            GUANINE     N1      -0.1153    0.0804   -0.1555    0.1405    145.12
                        C2       0.0226    0.0794   -0.1476    0.0825     74.12
                        N2       0.0815   -0.0390   -0.1661    0.0904    -25.55
                        N3       0.0952    0.1883   -0.1232    0.2109     63.18
                        C4       0.0180    0.2990   -0.1073    0.2995     86.55
                        C5      -0.1189    0.3095   -0.1133    0.3316    111.02
                        C6      -0.1964    0.1935   -0.1393    0.2758    135.43
                        O6      -0.3184    0.1830   -0.1485    0.3673    150.12
                        N7      -0.1590    0.4412   -0.0913    0.4690    109.82
                        C8      -0.0463    0.5055   -0.0728    0.5076     95.23
                        N9       0.0657    0.4256   -0.0810    0.4306     81.22

       ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            PHOSPHATE   P       -0.5666   -0.6529   -0.4477    0.8645   -130.95
                        O1      -0.6548   -0.5616   -0.3717    0.8627   -139.38
                        O2      -0.6319   -0.7714   -0.5077    0.9972   -129.32
                        O3      -0.4895   -0.5708   -0.5614    0.7520   -130.62
                        O5      -0.4451   -0.6999   -0.3548    0.8294   -122.45

            SUGAR       C1      -0.1641   -0.5038   -0.3296    0.5298   -108.04
                        C2      -0.1325   -0.6105   -0.2254    0.6247   -102.24
                        C3      -0.1116   -0.7334   -0.3137    0.7419    -98.65
                        C4      -0.2138   -0.7127   -0.4255    0.7441   -106.70
                        C5      -0.3448   -0.7874   -0.4099    0.8596   -113.65
                        O4      -0.2410   -0.5696   -0.4290    0.6185   -112.94

            CYTOSINE    N1      -0.2448   -0.3903   -0.2766    0.4608   -122.10
                        C2      -0.1802   -0.2688   -0.2560    0.3236   -123.84
                        O2      -0.0596   -0.2600   -0.2823    0.2668   -102.92
                        N3      -0.2520   -0.1641   -0.2077    0.3007   -146.93
                        C4      -0.3824   -0.1776   -0.1805    0.4216   -155.09
                        N4      -0.4480   -0.0726   -0.1336    0.4539   -170.79
                        C5      -0.4508   -0.3019   -0.2010    0.5425   -146.19
                        C6      -0.3772   -0.4052   -0.2493    0.5536   -132.95
