Re: [ccp4bb]: Matthews Parameter

[Manfred Buehner <buehner@biozentrum.uni-wuerzburg.de>]

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On Mon, 24 Mar 2003, Rufer, Arne {PRBD~Basel} wrote:

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> Dear collegues,
> I'm currently dealing with a dataset for which the Cell Content
> Analysis tool implemented in CCP4i gives a value of 1.6. Has anybody
> ever encountered such a low solvent content (i.e., 24.3 %)?

not quite as low, but I had 1.80 once (31 % solvent). This
was a small compact protein (16,000 Daltons) with a partial
specific volume of 0.744 ml/g.

Proteins differ not much in their density, but they do to
a small extent (maybe plus/minus 4 % for standard soluble
ones without attached carbohydrates, lipids, or nucleotides).
If you have a dense one (low partial specific volume, can be
calculated from the amino acid composition), this may ease your
bad feelings about too little solvent.

I wouldn't worry too much as long as I'm not getting close to
densest sphere packing ...
Especially if high scattering power indicates a well-ordered
cell.


> Is there any statitistics on this subject in the literature?
> Any suggestions are welcome (I already considered crystallization
> of a fragment).

that's definitely worth a thought. Mass spec would answer that.


Manfred
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 Dr. Manfred Buehner             Phone:  +49-931-888-4100
 Physiologische Chemie           FAX:    +49-931-888-4150
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 Email:  buehner@biozentrum.uni-wuerzburg.de
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