On a related note, how is the R factor calculated with twinned structures (i.e., how is Fcalc determined for the purposes of R factor calculation)? Thanks, Owen On Jun 3, 2010, at 10:27 AM, Nathaniel Echols wrote:

...

wrote: (see attached file) but only the last one seems to be used. Do I guess correctly that there is only provision for two domains adn therefore the last twinning definition overrides any

On Thu, Jun 3, 2010 at 6:52 AM, Pietro Roversi

Correct.

If so, is there a way of specifying and using multiple twinning domains/operators?

Currently phenix.refine is limited to a single twin operator.

-Nat

Hi Pietro, refinement of 4-domain twinning has been reported in CNS with adapted input scripts; see; http://www.ncbi.nlm.nih.gov/pubmed/15858272 The scripts are available through the IUCR electronic archive as supplementary material; http://journals.iucr.org/d/issues/2005/05/00/wd5026/wd5026sup1.zip Maybe this can be helpful for your case. Jonathan -- Jonathan Elegheert Ph.D. Student Unit for Structural Biology& Biophysics http://www.lprobe.ugent.be/xray.html Lab for Protein Biochemistry and Biomolecular Engineering Department of Biochemistry& Microbiology Ghent University, Belgium e-mail: [email protected] Op 6/3/2010 4:36 PM, Peter Zwart schreef:

Hi Owen,

R = |Fobs - Wcalc|/Fobs

Wcalc = sqrt( alpha Fcalc1^2 + Fcalc2^2(1-alpha) )

Sorry Pietro, only a single domain is possible at this moment.

Map coefficients are such that effects of twinning are not present

2010/6/3 Owen Pornillos:

...

On a related note, how is the R factor calculated with twinned structures (i.e., how is Fcalc determined for the purposes of R factor calculation)? Thanks, Owen

On Jun 3, 2010, at 10:27 AM, Nathaniel Echols wrote:

On Thu, Jun 3, 2010 at 6:52 AM, Pietro Roversi wrote:

...

(see attached file) but only the last one seems to be used. Do I guess correctly that there is only provision for two domains adn therefore the last twinning definition overrides any previously defined one?

Correct.

...

If so, is there a way of specifying and using multiple twinning domains/operators?

Currently phenix.refine is limited to a single twin operator. -Nat

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