Water-rich mixtures phenomena

It has been shown recently (1) that the transfer of urea from water to water-rich water-tetrahydrofuran (THF) mixtures is an entropy-controlled phenomenon (T AS°t > AH°t ), but from water to water-THF mixtures of mole fraction Z2 > 0.20 it is an enthalpy-controlled phenomenon ( AH°t > T AS°t ) moreover, the transfer is energetically favorable in the former case and unfavorable in the latter. A minimum in the standard free energy transfer... 

As shown in Table 3, in aqueous solution these short resilin-like peptides adopt a mixture of PPII stmcture, unordered conformations, and p-tums, while in Ttifluoroethanol (TFE) primarily type-11 p tums populate the conformational space. These findings are consistent with what Andersen has predicted and are also very similar to other elastomeric proteins studied. Interestingly, coacervation, a common phenomenon in elastin and abductin (in which a protein-rich phase is formed when the temperature is raised), has not been observed in resilin-like polypeptides (RLPs). This is almost certainly due to the inaeased hydrophilicity of resilin, which is soluble in water under all relevant experimental conditions. As mentioned above, additional spectroscopic studies on extended RLPs, as well as manipulations of RLP sequences via the introduction of different amino acid analogs and evaluation of corresponding conformational changes, would be useful to elucidate the mechanism of elasticity of resilin. 

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