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" <a.co...@medsch.ucl.ac.uk>:
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
