Differential scanning calorimetry study of the hydrophobic hydration of the elastin-based polypentapeptide, poly(VPGVG), from deficiency to excess of water

Abstract

The polypentapeptide of elastin, poly(VPGVG), has become an interesting model polypeptide in understanding the mechanism of protein folding and assembly. Due to its simple amino acid composition and the predominance of apolar side chains, this polymer shows strong hydrophobic–hydration phenomena. This paper explores, by calorimetric methods, the nature and structure of the clathrate‐like arrangements that take place, surrounding the apolar side chains of the polymer. The performance of these methods, especially differential scanning calorimetry, has a well‐gained reputation. In this work, the development of the clathrate‐like structures around this model polymer has been followed from water deficiency to water‐excess states. Two main conclusions have been obtained from the data obtained. First, there is an upper limit of about 170 water molecules per pentamer as the number of water molecules required to form all the possible clathrate‐like structures. Second, these structures exist as an inhomogeneous population with energies spreading in a significantly broad range, which is likely related to differences in geometrical parameters (bond lengths and angles) of the clathrate structure.© 2000 John Wiley & Sons, Inc. Biopoly 54: 282–288, 2000

Effect of α-, β- and γ-Cyclodextrins on the Inverse Temperature Transition of the Bioelastic Thermo-Responsive Polymer Poly(VPGVG)

“…This reduction in the total entropy change is in accordance with the data in literature, [35] since the reported values for DS inclusion in the vast majority of CD-inclusion compounds (including those with amino acids) are usually lower than the values for DS HH that can be deduced from calorimetric data on poly(VPGVG). [13,34] Therefore, in this case, the absolute value of the total entropy change would be reduced, which would cause an increase in the temperature needed for the phase separation to take place. This argument would be especially more plausible recalling that the amount of inclusions needed to render the observed shift in T t is likely small.…”

“…More details and data about synthesis and characterization of this polymer can be found elsewhere. [34] Turbidity Turbidity experiments were conducted in a Varian Cary 50 UV-Vis spectrophotometer with a thermostatized sample chamber. Turbidity was assessed by the change in absorbance at 300 nm of 40 mg/mL polymer solutions with the addition of variable amounts of the corresponding CD (see the "Results and Discussion" section).…”

Stimuli‐Responsive Thin Coatings Using Elastin‐Like Polymers for Biomedical Applications

“…The magnitude of the exothermic process is approximately one third of the magnitude of the endothermic process. [15,16,35] This means that, as more water molecules are dedicated to hydrophobic hydration (such as the case of increasingly hydrophobic ELPs), the contribution of the endothermic component increases, consequently increasing the value of DH. As previously described, the higher the pH, the more hydrophobic H-RGD6 becomes.…”

“…In this collapsed state, the chains become absent of ordered water molecules from the hydrophobic hydration and adopt a dynamic and regular structure known as b-spiral. [14][15][16] The recombinant nature of such polymers enables the introduction of peptide sequences through genetic engineering to extend their properties, including bioactive domains. [17][18][19] For example, Girotti et al [18] were able to biosynthesize an extracellular matrix analogue.…”

Thermoresponsive Self‐Assembly of Short Elastin‐Like Polypentapeptides and Their Poly(ethylene glycol) Derivatives

“…These tailor made block copolymers may then self-assemble into novel supramolecular structures, which possess functional properties suitable for drug delivery. [4,5] The hybrid systems are very often based on elastin-like peptides that undergo a reversible inverse temperature transition [6] accompanied by a conformational change on a molecular level. This can be observed by various spectral methods (e.g., NMR, IR, circular dichroism (CD) or Raman…”