Hi Alun,
If it's necessary in theory, and it's little effort, why not do it?
Even if in practise it may be not "necessary", I think not doing it is
a sign of sloppy science - on a par with not sequencing your inserts
to confirm absence of unwanted PCR mutations, checking by Edman
degradation or mass-spec that the protein you have expressed is really
the one you think it is, doing a proper map to confirm your ligand
density really is that, etc etc.
Am I a control freak? Perhaps, but I'd rather be a control freak than
a sloppy scientist. When 2 minutes effort can potentially avert weeks
of extra work in the future like discovering the difference in results
is due to an unknown mutation, discovering you crystallised the wrong
protein, reviewers rejecting your manuscript for not keeping the same
Free R set or doubting your ligand is really there, etc, I think it is
worth it...
Mark
Quoting "Alun R. Coker" <[log in to unmask]>:
> Hi All,
>
> I have been in the habit of transferring my initial free R assignments
> to any new data sets or to isomorphous data sets such as substrate
> complexes. Although theoretically this is necessary to obtain a valid
> free R many of my colleagues maintain that this is completely
> unnecessary in practice. Does anyone on the list have a view on this
> or has anyone tested to see if it makes any difference.
>
> Alun.
>
> --
> Alun R. Coker
> University College London
> Division of Medicine, Royal Free Campus
> Centre for Amyloidosis and Acute Phase Proteins
> Rowland Hill Street
> London
> NW32PF
>
> Tel: +44(0)20 7433 2764
> Fax: +44(0)20 7433 2776
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