Re: [ccp4bb]: unusually high solvent content

[Anastassis Perrakis <perrakis@nki.nl>]

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> According to Matthews, (Mathews, B. W. (1968). J. Mol. Biol. 33,
> 491-497.), the Matthew's coefficient of protein crystals is usually
> comprehended between 1.7-3.5 A3/Da.
> 
> Are there many proteins with a much higher solvent content that the
> Matthews limits?

Oh, yes. For a nice and extreme example read Weichenrieder at al, in 
Nature last year for the ALU RNP. 85 % solvent. The nice thing with it 
is that if you have 3.0 A data on a crystal with high solvent content 
you are much better of in refinement (and for ARP/wARP as well) than for 
a crystal with low solvent content and 3.0 A data (you get the same 
observations, but less parameters to fit, since your model is only 15% 
of the cell ...).

> Do you have experience with protein crystals with high solvent contents?

The bad news in the above is that usually crystals with high solvent 
content diffract badly. My personal experience from a random sampling of 
microfocus projects over three years at Grenoble is that crystals with 
high solvent tend to benefit more of a nice intense beamline like the 
microfocus. But no, I can not quantify that in any way ( I could try but 
a few people will jump on my throat and the stats would be weak, so I 
better leave it ..). BUT, now that I think of it again, there is at 
least one project with ~80% solvent for which the microfocus or the BW7B 
at Hamburg gave similar data (well, thats no flame to my old collegues 
near the Alpes, but the BW7B data were better - either better crystal or 
no crystal frying ...)

> 
> Could you point me some references to published works, or reviews about
> protein crystal structures with unusual VM (above 70%)?
> 
> Thanks in advance and Merry Christmas,
> Joao Miguel

Good luck, Tassos