TY - JOUR
T1 - Landscapes with megabasins
T2 - Polyamorphism in liquids and biopolymers and the role of nucleation in folding and folding diseases
AU - Angell, Charles
N1 - Funding Information:
Support of this program by the National Science Foundation under grant no. DMR9108028-002 is gratefully acknowledged. The author is grateful to P.G. Wolynes and E.I. Shakhnovich for valuable discussions.
PY - 1997
Y1 - 1997
N2 - We show how energy landscape concepts can rationalize the observations on glassforming liquids over the whole range of behavior, strong to fragile. In particular, we show how the existence of landscapes with both strong and fragile megabasins can provide a basis for understanding the nature of quasi-first-order transitions between amorphous states such as those observed to occur in the glassy states of "strong" glassformers. We show how this propensity originates in the liquid state and then emphasize the analogy provided, at the mesoscopic level, by the folding transition in proteins. Recognition that the folding transition is an equilibrium first-order transition between polyamorphic forms of a complex system implies recognition of the need for a nucleation step in the process. When nucleated phase transitions are kinetically retarded, their probability can be influenced by time-temperature history and by the presence of nucleating agents. Nucleation events are statistically rare in mesoscopic systems, hence the ability to fold rapidly should require special features in the folding molecular structure or the presence of nucleating agents. We propose that the unwanted folding events leading to pathogenic forms of certain proteins (prions) can be stimulated by nucleating agents, which thus may be the unidentified infectious agents in "mad cow" disease and related maladies.
AB - We show how energy landscape concepts can rationalize the observations on glassforming liquids over the whole range of behavior, strong to fragile. In particular, we show how the existence of landscapes with both strong and fragile megabasins can provide a basis for understanding the nature of quasi-first-order transitions between amorphous states such as those observed to occur in the glassy states of "strong" glassformers. We show how this propensity originates in the liquid state and then emphasize the analogy provided, at the mesoscopic level, by the folding transition in proteins. Recognition that the folding transition is an equilibrium first-order transition between polyamorphic forms of a complex system implies recognition of the need for a nucleation step in the process. When nucleated phase transitions are kinetically retarded, their probability can be influenced by time-temperature history and by the presence of nucleating agents. Nucleation events are statistically rare in mesoscopic systems, hence the ability to fold rapidly should require special features in the folding molecular structure or the presence of nucleating agents. We propose that the unwanted folding events leading to pathogenic forms of certain proteins (prions) can be stimulated by nucleating agents, which thus may be the unidentified infectious agents in "mad cow" disease and related maladies.
KW - Adam-Gibbs equation
KW - Folding transition in proteins
KW - Glassforming liquids
KW - Kauzmann paradox
KW - Nucleation
KW - Prions
KW - Relaxation functions
KW - Vogel-Fulcher equation
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U2 - 10.1016/S0167-2789(97)00077-8
DO - 10.1016/S0167-2789(97)00077-8
M3 - Article
AN - SCOPUS:22244438254
SN - 0167-2789
VL - 107
SP - 122
EP - 142
JO - Physica D: Nonlinear Phenomena
JF - Physica D: Nonlinear Phenomena
IS - 2-4
ER -