Dear Pat,
You don't say how large your ligand is, but if the occupancy is
refined as a single parameter so that all the atoms in the ligand
are constrained to have the same occupancy, it should be rather
well-defined and not highly correlated with the B-values. By
the way, I was not your referee!
Best wishes, George
Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-22582
On Sun, 31 May 2009, Patrick Loll wrote:
> Hi all,
>
> I'm looking for a reference to bolster my response to a referee, in which I
> defend my decision not to refine the occupancy of a ligand in structure
> refined at around 2 A resolution (note the ligand binding slte lies on a
> two-fold crystallographic axis, so the maximum occupancy is 0.5)
>
> I recall reading a paper a LONG time ago (decades) in which someone described
> some careful refinement experiments, and concluded that the correlation
> between occupancy and B-value is so strong that it simply makes no sense to
> "independently" refine both parameters (at least for light atoms, and in the
> absence of super high resolution data).
>
> Alas, all that I recall is this take-home message. I have no idea of where the
> paper appeared, or the names of the authors (or indeed, if I'm even
> remembering the paper's message correctly). I've tried trolling through Acta,
> without success. Does anyone have a better idea of where I might find this
> paper, or one espousing a similar message?
>
> Thanks,
>
> Pat
>
>
> -------------------------------------------------------------------------------------
> Patrick J. Loll, Ph. D. Professor of
> Biochemistry & Molecular Biology
> Director, Biochemistry Graduate Program
> Drexel University College of Medicine
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>
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