Transitions Inverse temperature

Urry, D.W., Entropic elastic processes in protein mechanisms. 1. Elastic structures due to an inverse temperature transition and elasticity due to internal chain dynamics, J. Prot. Chem., 7, 1-34, 1988. 

After expression of poly(VPGXG) genes, the biopolymer can easily be purified from a cellular lysate via a simple centrifugation procedure, because of the inverse temperature transition behavior. This causes the ELPs to undergo a reversible phase transition from being soluble to insoluble upon raising the temperature above the and then back to soluble by lowering the temperature below Tt (Fig. 9). The insoluble form can be induced via addition of salt [27]. The inverse transition can... 

In 2003, the van Hest group produced elastin-based side-chain polymers [123]. This research was motivated by the demonstration of the occurrence of an inverse temperature transition in a single repeat of VPGVG [124]. A methacrylate-functionalized VPGVG was synthesized and used as a monomer to perform atom transfer radical polymerization (ATRP) to produce homopolymers (Fig. 16b) or... 

Luan CH, Harris RD, Prasad KU et al (1990) Differential scanning calorimetry studies of the inverse temperature transition of the polypentapeptide of elastin and its analogs. Biopolymers 29 1699-1706... 

Urry DW, Trapane TL, McMichens RB et al (1986) N-15 nmr relaxation study of inverse temperature transitions in elastin pol)q)entapeptide and its cross-linked elastomer. Biopolymers 25 5209-5228... 

Three main characteristics emerge from these data. First, silks with different functions appear to have different conformations in solution second, we observe an inverse temperature transition to a /(-sheet or /(-turn like state and finally, silk crystallization requires temperatures that are much lower than those required for typical synthetic polymers. 

The azo-modified, elastin-like polypeptide XIV illustrated in Scheme 9 exhibits a so-called inverse temperature transition" that is, the compound gives cross-linked gels that remain swollen in water at temperature below 25 °C but deswell and contract upon a rise of temperature. The trans-cis photoisomerization of the azo units, obtained through alternating irradiation at 350 and 450 nm, permits photomodulation of the inverse temperature transition.[S9] The result indicates that attachment of a small proportion of azobenzene chromophores is sufficient to render inverse temperature transition of elastin-like polypeptides photoresponsive, and provides a route to protein-based polymeric materials capable of photomechanical transduction. 

Scheme 9 Chemical structure of the modified, elastin-like poly (pentapeptide) XIV, found to exhibit photomodulated inverse temperature transition. 59 ...

Euan, C.H. Urry, D.W. Solvent deuteration enhancement of hydrophobicity—DSC study of the inverse temperature transition of elastin-based polypeptides. Journal of Physical Chemistry 1991, 90, 7896-7900. 

Some polymers have been purified on the basis of their physicochemical properties. For example, silk-like polymers have been purified by taking advantage of their low solubility in aqueous medium (13). Elastin-like polymers (ELPs) have been purified by temperature cycling above and below their inverse temperature transition (Tt) (14). This technique has been extended to produce an ELP-tag that can be used to purify a number of recombinant proteins by temperature cycling, which may be faster and less expensive than affinity chromatography (15). 

Urry DW, Luan CH, Parker TM, Gowda DC, Prasad KU, Reid MC, Safavy A. Temperature of polypeptide inverse temperature transition depends on mean residue hydrophobicity. J Am Chem Soc 1991 113 4346-4348. 

Strzegowski LA, Martinez MB, Gowda DC, Urry DW, Tirrell DA. 1994. Photomodulation of the inverse temperature transition of a modified elastin poly(pentapeptide). J Am Chem Soc 116(2) 813 814. 

Table 1. Hydrophobicity scale for protein-based polymers and proteins based on the properties of the inverse temperature transition of elastic protein-based polymers, poly[/v(GVGVP), (GXGVP)]. ...

T[ and Tj, are the on-set temperature for the hydrophobic folding and assembly transition, that is, inverse temperature transition, in pbs (0.15 N NaCl, 0.01 M phosphate) as determined by light scattering and in water as determined by DSC, respectively. Both values are linearly extrapolated tofx = 1 and rounded to a number divisible by 5. AH and AS are the values at/x = 0.2 on the curve for a linear fit of the DSC derived endothermic heats and entropies of the transitions for die polymers in water. 

Table 3a. Composition effect on inverse temperature transition in water. ...

Table 3b. Effect of pH on inverse temperature transition of poly[0.82(GVGIP), 0.18(GEGIP)], (3)...

Table 3g. Cosolvent effect on inverse temperature transition of poly(GVGVP) in water.

Interestingly, this mechanical performance is accompanied by an extraordinary biocompatibiUty, although, however, the most striking properties are perhaps their acute smart and self-assembhng nature. These properties are based on a molecular transition of the polymer chain in the presence of water when their temperature is increased above a certain level. This transition, called the inverse temperature transition (ITT), has become the key issue in the development of new peptide-based polymers as molecular machines and materials. The understanding of the macroscopic properties of these materials in terms of the molecular processes taking place around the ITT has established a basis for their functional and rational design [102]. 

Figure 6 (a) Correlation between the turbidimetric profile as a function of temperature and differential scanning calorimetry (DSC) thermogram for a chemically synthesized polymer of (Val-Pro-Gly-Val-Gly) in water, (b) Photographic illustration of the phase behavior of poly(Val-Pro-Gly-Val-Gly) in aqueous solution at temperatures below (5 °C) and above (40 °C) the inverse temperature transition, 7,. Reprinted from Arias, F. J. Reboto, V. Martin, S. etal. Blotechnol. Lett. 2006,25(10), 687. Copyright 2006, with permission from Springer. 

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