Francis,
It's very easy to spot a 2-fold rotation or screw because the matrix
must be symmetric (or nearly so)**. Your matrix very obviously is not
(i,e, A12 ne A21, A13 ne A31 etc).
** Proof:
A rotation matrix is orthogonal, which implies inverse = transpose: A^-1 = A~.
A 2-fold rotation is proper which implies AA = I or A^-1 = A.
Take these together and you get A = A~ i.e. A is symmetric.
Surprising how many people aren't aware of this!
Cheers
-- Iann
On 21 February 2012 13:47, Francis E Reyes <[log in to unmask]> wrote:
> Hi all
>
> This structure has the following ncs (output via phenix.simple_ncs_from_pdb)
> OPERATOR 1
> CENTER: 18.3443 -55.4605 23.0986
>
> ROTA 1: 1.0000 0.0000 0.0000
> ROTA 2: 0.0000 1.0000 0.0000
> ROTA 3: 0.0000 0.0000 1.0000
> TRANS: 0.0000 0.0000 0.0000
>
> OPERATOR 2
> CENTER: 37.0405 -23.8676 -14.9388
>
> ROTA 1: -0.5444 -0.2202 0.8094
> ROTA 2: 0.8330 -0.0278 0.5526
> ROTA 3: -0.0991 0.9751 0.1985
> TRANS: 45.3456 -78.7231 53.0085
>
>
> It looks two-foldish but I'm not sure if it's proper or improper. (I'm trying to rationalize the lack of peaks on the self rotation maps).
>
>
> Any help would be appreciated.
>
> F
>
>
>
> ---------------------------------------------
> Francis E. Reyes M.Sc.
> 215 UCB
> University of Colorado at Boulder
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