Re: [ccp4bb]: p61 vs p65 flipped

[<hay.dvir@weizmann.ac.il>]

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Dear Ed,

> I'm trying to find Se sites in MAD data from crystals of space group p61 or
> p65. I was under the impression that the Patterson maps should be the same
> for both and that I therefore only needed to solve the Pattersons once.
> Experimental Patterson maps from peak data look the same for both. However,
> Solve is giving me different solutions for p61 compared with p65.

	Difference patterson map should look the same, since the Fourier
coefficients in the patterson  function are being squared. Therefore, from
the patterson you get two equivalent substructure solutions related to
each other by inversion.
	In most programs you should try both solutions to phase your
protein amplitudes. However, SOLVE has a built in automated routine to
guess the correct hand of your substructure. Thus, for a given space group
you provide with SOLVE you would get only one solution which probably
corresponds to the correct hand (as much as solve could guess) of the
substructure. However, if one of the space group you gave p61 or p65 are
correct, you should expect significantly different phase statistics and
maps. Correspondingly, The scores you find in solve.prt should be much
better for one of the space groups. And the protein maps should look like
of a protein with only one space group.

	Hope this helps !

Good luck!

Hay Dvir
Dept. of Structural Biology
Weizmann Institute of Science
Rehovot,	ISRAEL.