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[ccp4bb]: summary_smeared_reflections
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Ten days ago I posted a query regarding a strange diffraction pattern in
space group R32 which can be visited at:
http://www.mdc-berlin.de/~crystal/struc/structurelist.html
Several replies pointed me to the following papers which deal with
statistical layer disorder.
1) Howells and Perutz (1954) the structure of heamoglobin. V.
Imidazole-methaemoglobin: a further check of the signs.
Proc. Royal Soc. London Ser. A, 255, 308-314
2) Luo, Laver and Air (1992) Unusual diffraction of type B influenza
virus neuramidase crystals. Acta Cryst. A48, 742-744.
and
3) Bragg and Howells (1954) Acta Cryst 7 p409
4) Cochran and Howells (1954) Acta Cryst 7 p412
It took me a while to organise these papers and indeed it seems that
such statistical shifts (in both directions of layers) might be at the
origin of the smearing of distinct reflection layers while other
reflection layers remain sharp. Still intriguing to me is the fact that
the spots in our case don't fit exactly onto the lattice anymore. The
same has however also been observed in case of neuramidase (Luo et al).
Further suggestions dealt with crystal handling. We actually also
mounted crystals in capillaries, however still the same smearing.
Their seems to be some light on the horizon now by increasing the salt
concentration during the crystallisation ...
Many thanks to Karolin Luger, Gabby Rudenko, Remy Loris, Felix Vajdos,
Kay Diederichs and Shekhar Mande for suggestions and advice.
Best regards
Yves
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Yves Muller
Forschungsgruppe Kristallographie
Max-Delbrueck-Centrum fuer molekulare Medizin Tel: +49-30-9406-2725
Robert-Roessle-Str. 10 Fax: +49-30-9406-2548
D-13122 Berlin E-mail: yam@mdc-berlin.de
http://www.mdc-berlin.de/~crystal/cowork/yam.html
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