Chemical potential driven contraction and relaxation by ionic strength modulation of an inverse temperature transition

1988 ◽  
Vol 110 (10) ◽  
pp. 3303-3305 ◽  
Author(s):  
D. W. Urry ◽  
R. D. Harris ◽  
K. U. Prasad
Keyword(s):  
Ionic Strength ◽  
Chemical Potential ◽  
Inverse Temperature ◽  
Temperature Transition ◽  
Inverse Temperature Transition ◽  
Contraction And Relaxation

Biophysics of Energy Converting Model Proteins

1993 ◽  
Vol 330 ◽  
Author(s):  
D. W. Urry
Keyword(s):  
Chemical Potential ◽  
Molecular Machines ◽  
Mechanical Force ◽  
Inverse Temperature ◽  
Temperature Transition ◽  
Energy Inputs ◽  
Thermally Driven ◽  
Inverse Temperature Transition ◽  
And Function ◽  
Energy Converting

ABSTRACTThe biophysics of energy converting model proteins is presented as a general set of three postulates with fifteen corollaries for fifteen subtypes of molecular machines. All of the molecular machines utilize a common structural transition, an inverse temperature transition characterized by increased hydrophobic folding and/or assembly as the temperature is increased through a transition temperature range identified by Tt. These molecular machines, which can be polymers (e.g., proteins or protein-based polymers), are capable of interconverting the free energies involving the six intensive variables of mechanical force, temperature, pressure, chemical potential, electrochemical potential, and electromagnetic radiation.First-order molecular machines of the Tt-type are molecular engines which, with the appropriate energy input, can result in the production of useful mechanical motion. Postulate I is for the thermally-driven molecular engine. Postulate II with four corollaries is for the four cases where the energy inputs drive hydrophobic folding by lowering the temperature, Tt, at which the inverse temperature transition occurs. This is called the ΔTt-mechanism. The four energy inputs that have been shown to change the value of Tt are due to changes (1) in concentrations of chemicals, (2) in oxidative state of attached prosthetic groups, (3) in pressure, and (4) resulting from the absorption of light by attached chromophores. Postulate III with ten corollaries are for the ten pairwise energy conversions involving the intensive variables listed above exclusive of mechanical force. These energy conversions utilize the hydrophobic association transition but do not result in the motion implicit in the folding or assembly process. These are second-order molecular machines of the Tt-type.The physical basis for the ΔTt-mechanism of energy conversion of Postulates II and III is proposed to arise due to competition for hydration between apolar (hydrophobic) and polar moieties. This competition is capable of effecting large changes in pKa values of Glu, Asp, Lys and His residues. This mechanism is proposed to be a dominant process in protein folding, assembly, and function.

Self-Assembly of Hydrogels From Elastin-Mimetic Block Copolymers

2002 ◽  
Vol 724 ◽  
Author(s):  
Elizabeth R. Wright ◽  
R. Andrew McMillan ◽  
Alan Cooper ◽  
Robert P. Apkarian ◽  
Vincent P. Conticello
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Triblock Copolymers ◽  
Variable Temperature ◽  
Inverse Temperature ◽  
Temperature Transition ◽  
Scanning Calorimetry ◽  
Design Synthesis ◽  
Inverse Temperature Transition ◽  
Functional Biomaterials

AbstractTriblock copolymers have traditionally been synthesized with conventional organic components. However, triblock copolymers could be synthesized by the incorporation of two incompatible protein-based polymers. The polypeptides would differ in their hydrophobicity and confer unique physiochemical properties to the resultant materials. One protein-based polymer, based on a sequence of native elastin, that has been utilized in the synthesis of biomaterials is poly (Valine-Proline-Glycine-ValineGlycine) or poly(VPGVG) [1]. This polypeptide has been shown to have an inverse temperature transition that can be adjusted by non-conservative amino acid substitutions in the fourth position [2]. By combining polypeptide blocks with different inverse temperature transition values due to hydrophobicity differences, we expect to produce amphiphilic polypeptides capable of self-assembly into hydrogels. Our research examines the design, synthesis and characterization of elastin-mimetic block copolymers as functional biomaterials. The methods that are used for the characterization include variable temperature 1D and 2D High-Resolution-NMR, cryo-High Resolutions Scanning Electron Microscopy and Differential Scanning Calorimetry.

Effect of NaCl on the Exothermic and Endothermic Components of the Inverse Temperature Transition of a Model Elastin-like Polymer

2007 ◽  
Vol 8 (2) ◽  
pp. 354-358 ◽  
Author(s):  
Javier Reguera ◽  
Dan W. Urry ◽  
Timothy M. Parker ◽  
David T. McPherson ◽  
J. Carlos Rodríguez-Cabello
Keyword(s):  
Inverse Temperature ◽  
Temperature Transition ◽  
Inverse Temperature Transition

Influence of the Molecular Weight on the Inverse Temperature Transition of a Model Genetically Engineered Elastin-like pH-Responsive Polymer

2004 ◽  
Vol 37 (9) ◽  
pp. 3396-3400 ◽  
Author(s):  
Alessandra Girotti ◽  
Javier Reguera ◽  
Francisco Javier Arias ◽  
Matilde Alonso ◽  
Ana María Testera ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Genetically Engineered ◽  
Inverse Temperature ◽  
Ph Responsive ◽  
Temperature Transition ◽  
Responsive Polymer ◽  
Inverse Temperature Transition
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