Gelation: the role of sugars and polyols on gelatin and agarose.
Gelation is enhanced by the addition of sugars and polyols. How, at a microscopic level, do such cosolvents enhance gelation? The following two different hypotheses have been proposed so far to answer this question: (i) enhancement of water structure around the biopolymer induced by cosolvents; (ii) exclusion of cosolvents from biopolymer surfaces. To examine the validity of the above hypotheses, as well as to quantify the driving forces of cosolvent-induced gelation, we have constructed a statistical thermodynamic theory of gelation, by extending our Kirkwood-Buff theory of cosolvency; biopolymer-water and biopolymer-cosolvent interactions can both be determined from thermodynamic data. The exclusion of cosolvents is shown to be the dominant contribution, whereas the hydration change is a minor contribution, which may be important only so far as to mediate the exclusion of cosolvents.
York Structural Biology Laboratory, Department of Chemistry, University of York , Heslington, York YO10 5YW, United Kingdom.
Seishi
S
Shimizu
Nobuyuki
N
Matubayasi
D002241:Carbohydrates / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D012685:Sepharose / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D002241:Carbohydrates; D005782:Gels; D011108:Polymers; C024617:polyol; D014867:Water; D005780:Gelatin; D012685:Sepharose