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This story is indeed sad. However, we must appreciate and acknowledge
the fact that Geoffrey Chang has been fast at putting the record
straight once the error was found.

Thinking (perhaps too hastily) about this case, there is, in my opinion,
at least something to learn, or better, something that we, as
scientists, should never forget: our results are no more and no less
questionable than any other results. And apparently, there were in this
case serious problems of consistency with biochemical data. Of course,
any could have been wrong, but we tend to think that it's always the
others' mistake. Knowing that this is common human behaviour, we should
be aware of it.

On the other hand, this sad story adds a turn to the recent discussion
on depositing structure factors. The structure factors of only one of
the five structures (1z2r) were deposited. And for this case, EDS didn't
produce a map because, the server says, its calculated map had an
Rfactor of 0.369 compared to the published 0.28 The coordinates are
still available today at the EBI (they are already marked obsolete, at
the authors request, at the RCSB), but the structure factors of the 1z2r
structure cannot be retrieved, so it is impossible to me to know what
information was in them. I think this case shows the importance of
including all relevant raw data used to solve and refine a structure,
i.e. all wavelengths, anomalous pairs, etc.

Then, there are other considerations, like those raised by David
Schuller about the publishers policies, and I would add the pressure to
publish in "high-profile" journals for researchers to get funds or even
not to be sacked. Science is done in a society context that often gets
ignored.

In any case, I am quite optimistic in the sense that the immense
majority of structures produced nowadays seem not to have such serious
errors. Having said so, I think that we should put the means to make
sure this continues to be the case, and possibly the best way is to
force the availability of all relevant data _and_ the validation of such
data with a set of tools that should be agreed by consensus. Whether
these steps should be taken prior or after publication is another
discussion. But at least, when doubts would appear we should have the
best materials and tools to investigating at them.

Cheers,



Miguel

En/na Arun Malhotra ha escrit:
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> 
> 
> 
> I was shocked to see the retraction in yesterday's issue of Science (Dec
> 22, 2006) of several ABC transporter structures and papers from the
> Chang lab, including three published in Science.  The retraction says
> that the structures have the wrong hand and topology due to an
> "in-house" program that inverted the signs on the anomalous pairs.
> 
> I have no expertise in ABC transporters, but were there warning signs in
> the structures? Were red flags raised by PDB or the other servers such
> as EDI, EDS, etc.? Looking at some of these papers, these are low
> resolution structure and I see very high R/Rfree, but there must have
> been other signs of problems as well.
> 
> In the past few years, there have been almost no structures retracted
> due to gross errors and the checks being used by structural biology
> community seemed to working quite well - what can we learn from this
> tragic and sad error ?
> 

- --
Miguel Ortiz Lombardía
Centro de Investigaciones Oncológicas
C/ Melchor Fernández Almagro, 3
28029 Madrid, Spain
Tel. +34 912 246 900
Fax. +34 912 246 976
e-mail: [EMAIL PROTECTED]
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Et ainsi ne pouvant faire que ce qui est juste fût fort, on a fait que
ce qui est fort fût juste.
                                                Blaise Pascal, Pensées
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