Thank you all for the replies.
Sorry for taking so long to reply, I was actually trying some of your
interesting ideas (and I'm still trying).
I tried using the low resolution data sets for the molecular replacement
(thanks to Yuriy Patskovsky), I also improved and increased my coiled
coil database and employed it in many approaches using EPRM (interesting
program I was not aware of), which I found to produce lots of data,
hopefully addressing at some extent the helixes bent (thanks to Bernhard
Rupp). I also tried some more tweaking in Phaser, although not sure if
did it properly (thanks to Randy Read).
There is no twinning as far as I can tell (thanks to Ed Pozharski for
the tip). Using a data set with enough completeness (360 degrees @
Brookhaven) and processing in P1 did not help me because in this space
group there is most likely 2-3 helixes in the asymmetric unit, which
complicates the problem (and it takes a lot of time for Phaser to run).
Automated approaches also did not yield a better result (as far as I can
tell). I'm convinced that the space group is C2221, but I may be wrong.
Thanks to Sergei Strelkov for the numerous useful suggestions on how to
approach the problem.
One of the big issues for me is to discriminate between a lot of
similarly good density maps. For example:
http://www.fullonline.org/coils/coil1.jpg
http://www.fullonline.org/coils/coil2.jpg
I have hundreds of solutions like these and I think they are all wrong.
I couldn't manage to run Arcimboldo, could not find a tutorial on it
either. It was highly recommended here (and elsewhere), so I'm
definitely willing to give it a try (thanks Isabel Uson).
You guys opened my eyes about a series of issues that I should learn
about and approach, I'm most thankful for that.
Best regards,
Napo