ti
> Sent: Thursday, February 8, 2024 00:24
> To: CCP4BB@JISCMAIL.AC.UK
> Subject: Re: [ccp4bb] what is isomorphous?
>
> Hello!
>
> I have to admit my maths is a bit lazy, but this discussion got me stitched
> up,
> because of a point I believe has not been addressed: the
important for two lysozyme data
> sets to scale together. The Rmerge for the two dehydration states was
> something crazy large, like 44%, even though under the standard 'rules'
> (more rules of thumb), one would have believed that these data sets should
> have been 'isomorphous'. For t
ame dehydration state, the data merged with
'typical' statistics of lysozyme (like 3-4%).
James will have the details that I do not.
cheers, tom
*From:* CCP4 bulletin board on behalf of Randy
John Read
*Sent:* Thursday, December 21, 2023 10:53 PM
*To:* CCP4BB@JISCMAIL.
, 2023 10:53 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] what is isomorphous?
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I think we’ve strayed a bit from Doeke’s original question involving crystals
A, B
o be similar.
Best wishes to all.
Doeke
-Original Message-
From: CCP4 bulletin board On Behalf Of Randy John Read
Sent: Thursday, December 21, 2023 6:53 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] what is isomorphous?
I think we’ve strayed a bit from Doeke’s original question invo
I think we’ve strayed a bit from Doeke’s original question involving crystals
A, B and C, where I think the consensus opinion would be that we would refer to
crystal C as not being isomorphous to either A or B.
On the question of what “isomorphous” means in the context of related crystals,
I’m
Hello Harry,
I think this is the paper you mean:
https://scripts.iucr.org/cgi-bin/paper?S0365110X56002552
They gave depressingly low estimates of how much the cell dimensions could
change in order for isomorphous replacement to still work. In reality, unit
cells can shrink and swell, but the
Hi
Didn’t Francis Crick have something to say about this in the early 1950s? I’m
sure it was published but off the top of my mind I can’t think where (one of
the more “established” members of this community will be able to give chapter
and verse)!
If you want to read something a little more
Hi Doeke,
you can take the coordinates of B and do a rigid body refinement
against the data from A. If this map is sufficient to reproduce model A
(including model building and more refinement cycles), then B is
isomorphous to A. You can do this the other way round, and the result
may not be the
From: CCP4 bulletin board On Behalf Of Marius Schmidt
Sent: Wednesday, December 20, 2023 14:36
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] what is isomorphous?
According to Jon, Isomorphous Replacement ALWAYS works,
because it is only supposed to be isomorphous.
Isomorphous difference
10-dmarc-requ...@jiscmail.ac.uk>
Sent: Wednesday, December 20, 2023 4:21 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] what is isomorphous?
Unless you have a degree in maths, the IUCr's "Little Dictionary of
Crystallography" by A. Authier and G. Chapuis (2014) defies comprehension
My apologies my second paragraph was badly wrong. What Ian Tickle said in 2008
(and to save him writing it all again ;-) is:
"In general crystallographic usage 'isomorphous' refers to the similarity of
crystal structures,
i.e. same arrangement of atoms in the a.u. and the same symmetry. So
Unless you have a degree in maths, the IUCr's "Little Dictionary of
Crystallography" by A. Authier and G. Chapuis (2014) defies comprehension on
this matter (it's all to do with set / group theory, I think, and there are
many more morphisms covered in about 6 pages: homo, epi, mono, endo,
Dear colleagues,
Something to muse over during the holidays:
Let's say we have three crystal forms of the same protein, for example
crystallized with different ligands. Crystal forms A and B have the same
crystal packing, except that one unit cell dimension differs by, for example,
3%.
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