Hi all,
I have a tricky molecular replacement case. One protein in two different crystal forms: hexagonal with 1 mol/asu, triclinic with 2 mol/asu (based on packing and self rotation).

No experimental phases are available this far, however, there is a distant homology model. For the hexagonal crystals, phaser gives a solution with really good scores (Z > 9, -LLG > 50) and a good packing. While the correct solution is way down the list in the RF, the TF can separate it from the bulk of bad solutions. Slight changes in the model give the same solution. Maps are somehow ok, however, not good enough to enable arpwarp to build the model. It does not totally blow up either.

For the triclinic crystal form with 2 molecules related by a two-fold which is not parallel to a crystal axis, phaser does not find a solution. Neither does molrep using the locked rotation function with the two-fold extracted by the SRF.

As the homology between the data set should be higher than between the model in the data sets and the search model, I tried a cross rotation function between the two data sets. Strong peaks there should give the relation between the orientation of the molecule in the hexagonal crystal (that I believe I can find). With two rotations known and one translation undefined, I'd be left with only one translation that needs to be found. Then averaging within P1 or cross crystal might improve the density...

Almn appears to be the only program in ccp4 that can do a cross rotation using Fs only, right?? I used the P1 data as hklin, the hexagonal data as hklin2. Almn comes back with two strong peaks (see below), however, now I am lost:
- the first two peaks appear to be the same
- are the Euler angles the ones I could use in a peak list for eg. Phaser?
- does this procedure make sense at all?
- any other ideas?

Thanks a lot
Jan

almn.log:
##########
  Peaks must be greater than     2.00  times RMS density     52.2161



                        Eulerian angles                       Polar angles

                     Alpha   Beta  Gamma       Peak       Omega    Phi  Kappa           Direction cosines
PkNo Symm: 1   2

 Peak   1
      1   1   1      323.7  143.4   18.5      540.8        92.9   62.6  143.8        0.4594  0.8867 -0.0511
      1   1   2      323.7  143.4   78.5      540.8        83.2   32.6  145.9        0.8364  0.5351  0.1184
      1   1   3      323.7  143.4  138.5      540.8        75.6    2.6  157.2        0.9674  0.0441  0.2495
      1   1   4      323.7  143.4  198.5      540.8        71.9  332.6  174.4        0.8439 -0.4373  0.3108
      1   1   5      323.7  143.4  258.5      540.8       107.2  122.6  167.0       -0.5149  0.8049 -0.2950
      1   1   6      323.7  143.4  318.5      540.8       101.7   92.6  151.7       -0.0446  0.9781 -0.2034
      1   1   7      143.7   36.6   41.5      540.8       161.7  321.1  175.0        0.2448 -0.1974 -0.9493
      1   1   8      143.7   36.6  341.5      540.8        20.4  171.1  128.2       -0.3451  0.0540  0.9370
      1   1   9      143.7   36.6  281.5      540.8        31.6  201.1   73.8       -0.4882 -0.1885  0.8521
      1   1  10      143.7   36.6  221.5      540.8        82.2  231.1   37.0       -0.6220 -0.7711  0.1363
      1   1  11      143.7   36.6  161.5      540.8       144.3  261.1   65.1       -0.0902 -0.5770 -0.8118
      1   1  12      143.7   36.6  101.5      540.8       158.6  291.1  118.5        0.1317 -0.3411 -0.9307

 Peak   2
      2   1   1      143.7   36.6   41.5      540.8       161.7  321.1  175.0        0.2448 -0.1974 -0.9493
      2   1   2      143.7   36.6  101.5      540.8       158.6  291.1  118.5        0.1317 -0.3411 -0.9307
      2   1   3      143.7   36.6  161.5      540.8       144.3  261.1   65.1       -0.0902 -0.5770 -0.8118
      2   1   4      143.7   36.6  221.5      540.8        82.2  231.1   37.0       -0.6220 -0.7711  0.1363
      2   1   5      143.7   36.6  281.5      540.8        31.6  201.1   73.8       -0.4882 -0.1885  0.8521
      2   1   6      143.7   36.6  341.5      540.8        20.4  171.1  128.2       -0.3451  0.0540  0.9370
      2   1   7      323.7  143.4   18.5      540.8        92.9   62.6  143.8        0.4594  0.8867 -0.0511
      2   1   8      323.7  143.4  318.5      540.8       101.7   92.6  151.7       -0.0446  0.9781 -0.2034
      2   1   9      323.7  143.4  258.5      540.8       107.2  122.6  167.0       -0.5149  0.8049 -0.2950
      2   1  10      323.7  143.4  198.5      540.8        71.9  332.6  174.4        0.8439 -0.4373  0.3108
      2   1  11      323.7  143.4  138.5      540.8        75.6    2.6  157.2        0.9674  0.0441  0.2495
      2   1  12      323.7  143.4   78.5      540.8        83.2   32.6  145.9        0.8364  0.5351  0.1184

 Peak   3
      3   1   1      335.2   54.5   36.5      209.2        78.8   59.3   55.6        0.5006  0.8437  0.1940 ...
 Peak   4
      4   1   1      155.2  125.5   23.5      209.2        62.8  155.8  179.4       -0.8112  0.3638  0.4579 ...
 Peak   5
      5   1   1      349.3   53.8   13.0      176.4        87.7   78.2   53.9        0.2051  0.9779  0.0406 ...