Hi:
Is the resolution of the data sufficient to apply direct methods to find
only the copper atoms, then use the copper atom positions in an
old-fashioned
'heavy-atom' phasing method, combined with direct methods?
Incidentally, was the following publication of any relevance in your
efforts?
Acta Crystallogr D Biol Crystallogr. 1998 Jul 1;54(Pt 4):629-35.
Structure determination of a 16.8 kDa copper protein at 2.1 A
resolution using anomalous scattering data with direct methods.
Harvey I, Hao Q, Duke EM, Ingledew WJ, Hasnain SS.
ES
University of Madras
Yi Xue wrote:
>Dear all:
> We already got nice crystals of a drug-protein complex, however, MR
>failed due to the huge copies (>12) of protein molecules per asu. Protein
>itself is a small one, only ~70 aa.
> Later on, we collected MAD data of copper (copper : protein ~ 1: 1),
>Rsym of the data was around ~9%, the anomalous signals were weak, and only
>good to ~6A, the data also failed to solve the phases.
> Thus, basically, the Cu anomallous signal is very weak, and the
>crystals are kind of sensitive to radiation, it is dying but not that fast.
> I am wondering, Do we stand any chances to solve the phases by Cu MAD
>or SAD?
>
>
>Any suggestions or comments are highly appreciated?
>Yi
>
>
>
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