A forum for discussing the behaviour of water in the living cell
Saturday, December 22, 2007
Chem Rev article is now online
My review article on water in cell biology has now been published online in Chemical Reviews – it’s available here. Some minor corrections in the first five pages were omitted (I’m hoping these might yet be fixed), but such is life. Hope it’s useful.
Biophys J. 2006 Dec 1;91(11):4201-9. Epub 2006 Sep 15.
Resurrecting abandoned proteins with pure water: CD and NMR studies of protein fragments solubilized in salt-free water.
Li M, Liu J, Ran X, Fang M, Shi J, Qin H, Goh JM, Song J. Department of Biological Sciences, Faculty of Science, Yong Loo Lin School of Mediciine, National Univeristy of Singapore, Singapore.
Many proteins expressed in Escherichia coli cells form inclusion bodies that are neither refoldable nor soluble in buffers. Very surprisingly, we recently discovered that all 11 buffer-insoluble protein fragments/domains we have, with a great diversity of cellular function, location, and molecular size, could be easily solubilized in salt-free water. The circular dichroism (CD) and NMR characterization led to classification of these proteins into three groups: group 1, with no secondary structure by CD and with narrowly-dispersed but sharp (1)H-(15)N heteronuclear single quantum correlation (HSQC) peaks; group 2, with secondary structure by CD but with HSQC peaks broadened and, consequently, only a small set of peaks detectable; and group 3, with secondary structure by CD and also well-separated HSQC peaks. Intriguingly, we failed to find any protein with a tight tertiary packing. Therefore, we propose that buffer-insoluble proteins may lack intrinsic ability to reach or/and to maintain a well-packed conformation, and thus are trapped in partially-folded states with many hydrophobic side chains exposed to the bulk solvent. As such, a very low ionic strength is sufficient to screen out intrinsic repulsive interactions and, consequently, allow the hydrophobic clustering/aggregation to occur. Marvelously enough, it appears that in pure water, proteins have the potential to manifest their full spectrum of structural states by utilizing intrinsic repulsive interactions to suppress the attractive hydrophobic clustering. Our discovery not only gives a novel insight into the properties of insoluble proteins, but also sheds the first light that we know of on previously unknown regimes associated with proteins.
I am a London-based writer, and the author of several books on aspects of science and its interactions with other aspects of culture. My latest book is The Modern Myths (University of Chicago Press, 2021).
5 comments:
Many congratulations on a wonderful, extensively-researched review.
Dear Phili
I have read your paper with great interest.
Do you have any comments on this paper?
http://www.biophysj.org/cgi/content/full/91/11/4201
Biophys J. 2006 Dec 1;91(11):4201-9. Epub 2006 Sep 15.
Resurrecting abandoned proteins with pure water: CD and NMR studies of protein fragments solubilized in salt-free water.
Li M, Liu J, Ran X, Fang M, Shi J, Qin H, Goh JM, Song J.
Department of Biological Sciences, Faculty of Science, Yong Loo Lin School of Mediciine, National Univeristy of Singapore, Singapore.
Many proteins expressed in Escherichia coli cells form inclusion bodies that are neither refoldable nor soluble in buffers. Very surprisingly, we recently discovered that all 11 buffer-insoluble protein fragments/domains we have, with a great diversity of cellular function, location, and molecular size, could be easily solubilized in salt-free water. The circular dichroism (CD) and NMR characterization led to classification of these proteins into three groups: group 1, with no secondary structure by CD and with narrowly-dispersed but sharp (1)H-(15)N heteronuclear single quantum correlation (HSQC) peaks; group 2, with secondary structure by CD but with HSQC peaks broadened and, consequently, only a small set of peaks detectable; and group 3, with secondary structure by CD and also well-separated HSQC peaks. Intriguingly, we failed to find any protein with a tight tertiary packing. Therefore, we propose that buffer-insoluble proteins may lack intrinsic ability to reach or/and to maintain a well-packed conformation, and thus are trapped in partially-folded states with many hydrophobic side chains exposed to the bulk solvent. As such, a very low ionic strength is sufficient to screen out intrinsic repulsive interactions and, consequently, allow the hydrophobic clustering/aggregation to occur. Marvelously enough, it appears that in pure water, proteins have the potential to manifest their full spectrum of structural states by utilizing intrinsic repulsive interactions to suppress the attractive hydrophobic clustering. Our discovery not only gives a novel insight into the properties of insoluble proteins, but also sheds the first light that we know of on previously unknown regimes associated with proteins.
Very interesting indeed - thanks wufei!
A very low ionic strength is sufficient to screen out intrinsic repulsive interactions.
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