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Re: finding sites
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> I have two different space groups...P21 and P1. Most of my work is on
> the P21 form as the P1 form is a recent discovery. I have collected
> Theoretically, the 3 dimensional arrangements of the sites should be the
> same in both space groups, so I was wondering if I can use the known
> sites as a sort of MR search model against the isomorphous signal from P1
> Native vs. Semet. I don't know exactly how I would go about doing that,
> but if anybody has some suggestions, they would be greatly appreciated.
1. Use |Fph-Fp| as the "native" data
2. You didnt say if you knew how the Se sites "clustered" (i.e. know
which belong to the same molecule), but assuming that you do:
Isomorphous difference Se-S = 18 electrons, which is approximately
that of sulphur (16 electrons), so you could create a "SeMet"
MR model of a set of sulphurs at each SeMet site.
3. Run MR in the normal way.
Alternatively, by creatively editing the script in X-PLOR for doing
Patterson space rotation functions, you could probably do the same
analogous thing using the anomalous difference patterson in P1.
I've had some success using |Fph-Fp| in translation functions to find
heavy atom sites in proteins, although this is certainly not a new idea,
but I've never tried rotation functions before.
phil
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| Phil Jeffrey | |
| Crystallography Facility Manager | If you lie to the compiler, |
| Memorial Sloan-Kettering Cancer Center, NYC | it will get its revenge |
| phil@xray2.mskcc.org | - Henry Spencer |
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