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  From: Thomas M Laue <>
  To  : Geoff=Howlett%BioChem%UNIMELB@muwaye.unimelb.EDU.AU
  Date: Thu, 23 Jun 1994 09:46:24 -0400 (EDT)

Re: vbars of triacylglycerols and nucleic acids

I highly recommend the article by Durschlag in:
Thermodynamic Data for Biochemistry and Biotechnology
H.-J. Hinz (ed.) Springer-Verlag, Berlin, Heidelberg, New York, Tokyo
This book is a real treasure. There are tables for the materials you 
asked about (under different conditions) and a really well-done 
discussion about v-bar.

As long as we are back on the topic of v-bar, there is a very nice review
by Gross and Jaenicke in Eur. J. Biochem. 221:617-630 (1994) about
pressure effects and proteins. In particular, there is a nice graph of the
correlation between adiabatic compressibility and v-bar. There is a nice 
correlation between compressibility and v-bar, similar to what Waugh 
speculated might be the case if proteins contain significant void regions 
(i.e. no solvent).

This gets back to my question concerning a structural excuse abnormally
high v-bars, and my comment that there seemed to be some correlation with
disulfide formation. The most interesting result is with thioredoxin,
where oxidation of the disulfide leads to an increase in v-bar from 0.75
ml/g to nearly 0.8 ml/g. To quote from the article, "At present, no
explanation for this spectacular increase in volume and compressibility 
of E. coli thioredoxin can be provided. The authors speculate about 
cooperative effects in the solvent interface, which, however, still await 
to be specified and proven."

Finally, the article indicates that proteins containing significant 
amounts of alpha helix are more prone to being compressible (too high a 
vbar) than ones containing lots of beta sheet.

Thanks for the excuse to unload what I have found about vbar!
Tom Laue

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