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Macromolecular crowding and its conequences

Johansson, Hans-Olof LU ; Brooks, D E and Haynes, C A (2000) In International Review of Cytology 192. p.155-170
Abstract
Incompatible pairs of polymers separate into two phases in aqueous solution above a few percentage points total concentration. Protein pairs can also produce phase separation, but at somewhat higher concentrations. In this chapter, we explore the effect of high background concentrations of macromolecules on phase separation of pairs of species which would not be at sufficiently high concentration to separate in the absence of the uninvolved species. Effects produced by such high background concentrations are known as macromolecular crowding. Dramatic enhancements in various association reactions due to crowding have been predicted and observed but its effects on phase separation in biological mixtures typical of the cytoplasm have not been... (More)
Incompatible pairs of polymers separate into two phases in aqueous solution above a few percentage points total concentration. Protein pairs can also produce phase separation, but at somewhat higher concentrations. In this chapter, we explore the effect of high background concentrations of macromolecules on phase separation of pairs of species which would not be at sufficiently high concentration to separate in the absence of the uninvolved species. Effects produced by such high background concentrations are known as macromolecular crowding. Dramatic enhancements in various association reactions due to crowding have been predicted and observed but its effects on phase separation in biological mixtures typical of the cytoplasm have not been examined. Here, we describe a calculation based on the Flory-Huggins treatment of concentrated polymer solutions that sheds some light on this issue. We find that a background of 20 wt % of a high molecular weight species greatly reduces the concentrations needed to produce phase separation in a mixture of two incompatible macromolecules if one is more hydrophobic than the other. Given the high total concentration of macromolecules in cytoplasm, it is perhaps surprising that phases have not been observed. This issue is discussed and some explanations offered. (Less)
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published
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keywords
scaled particle theory, Flory-Huggins theory, incompatibilty, phase diagrams
in
International Review of Cytology
volume
192
pages
155 - 170
publisher
Academic Press
ISSN
0074-7696
language
English
LU publication?
yes
id
c48c7d3d-0189-4fbe-8b8b-7e23f9425c16 (old id 125113)
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http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=10553278&dopt=Abstract&holding=f1000%2Cf1000m%2Cisrctn
date added to LUP
2007-07-05 16:33:53
date last changed
2016-04-16 05:34:35
@article{c48c7d3d-0189-4fbe-8b8b-7e23f9425c16,
  abstract     = {Incompatible pairs of polymers separate into two phases in aqueous solution above a few percentage points total concentration. Protein pairs can also produce phase separation, but at somewhat higher concentrations. In this chapter, we explore the effect of high background concentrations of macromolecules on phase separation of pairs of species which would not be at sufficiently high concentration to separate in the absence of the uninvolved species. Effects produced by such high background concentrations are known as macromolecular crowding. Dramatic enhancements in various association reactions due to crowding have been predicted and observed but its effects on phase separation in biological mixtures typical of the cytoplasm have not been examined. Here, we describe a calculation based on the Flory-Huggins treatment of concentrated polymer solutions that sheds some light on this issue. We find that a background of 20 wt % of a high molecular weight species greatly reduces the concentrations needed to produce phase separation in a mixture of two incompatible macromolecules if one is more hydrophobic than the other. Given the high total concentration of macromolecules in cytoplasm, it is perhaps surprising that phases have not been observed. This issue is discussed and some explanations offered.},
  author       = {Johansson, Hans-Olof and Brooks, D E and Haynes, C A},
  issn         = {0074-7696},
  keyword      = {scaled particle theory,Flory-Huggins theory,incompatibilty,phase diagrams},
  language     = {eng},
  pages        = {155--170},
  publisher    = {Academic Press},
  series       = {International Review of Cytology},
  title        = {Macromolecular crowding and its conequences},
  volume       = {192},
  year         = {2000},
}