Characterizations of critical processes in liquid-liquid phase separation of the elastomeric protein-water system: Microscopic observations and light scattering measurements

Kaibara, Kozue; Watanabe, Takayuki; Miyakawa, Kenji

doi:10.1002/(sici)1097-0282(20000415)53:5<369::aid-bip2>3.0.co;2-5

Cited by 23 publications

(7 citation statements)

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“…3 Indeed, the increase in turbidity is due to the formation of microscopic oil-like droplets, or microcoacervates, as the solution is heated (45). However, on the basis of model fitting to absorbance measurements for soluble tropoelastin (Fig.…”

Section: Properties Of Human Tropoelastinmentioning

confidence: 99%

Thermodynamic and Hydrodynamic Properties of Human Tropoelastin

Toonkool¹,

Regan²,

Kuchel³

et al. 2001

Journal of Biological Chemistry

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Tropoelastin is the soluble precursor of elastin that bestows tissue elasticity in vertebrates. Tropoelastin is soluble at 20°C in phosphate-buffered saline, pH 7.4, but at 37°C equilibrium is established between soluble protein and insoluble coacervate. Sedimentation equilibrium studies performed before (20°C) and after (37°C) coacervation showed that the soluble component was strictly monomeric. Sedimentation velocity experiments revealed that at both temperatures soluble tropoelastin exists as two independently sedimenting monomeric species present in approximately equal concentrations. Species 1 had a frictional ratio at both temperatures of ϳ2.2, suggesting a very highly expanded or asymmetric protein. Species 2 displayed a frictional ratio at 20°C of 1.4 that increased to 1.7 at 37°C, indicating a compact and symmetrical conformation that expanded or became asymmetric at the higher temperature. The slow interconversion of the two monomeric species contrasts with the rapid and reversible process of coacervation suggesting both efficiently incorporate into the coacervate. A hydrated protein of equivalent molecular weight modeled as a sphere and a flexible chain was predicted to have a frictional ratio of 1.2 and 1.6, respectively. Tropoelastin appeared as a single species when studied by pulsed field-gradient spinecho NMR, but computer modeling showed that the method was insensitive to the presence of two species of equal concentration having similar diffusion coefficients. Scintillation proximity assays using radiolabeled tropoelastin and sedimentation analysis showed that the coacervation at 37°C was a highly cooperative monomer-n-mer self-association. A critical concentration of 3.4 g/liter was obtained when the coacervate was modeled as a helical polymer formed from the monomers via oligomeric intermediates.Elastin forms a highly insoluble cross-linked extracellular matrix that is predominantly responsible for the elasticity of vertebrate tissue. The precursor of elastin, tropoelastin, is devoid of cross-links. Following secretion from the cell surface, tropoelastin undergoes coacervation, which is a process of selfassociation characterized by an inverse temperature transition (1). Tropoelastin is soluble in aqueous solution at room temperature in vitro, but upon raising the temperature to 37°C the solution becomes turbid as tropoelastin molecules associate to form large aggregates (2, 3). This process of coacervation results from multiple intermolecular interactions of the hydrophobic domains (3, 4). The tropoelastin coacervate is a thick viscoelastic phase that is not miscible with the overlying solution (5). On cooling to 20°C, the aggregates dissociate reversibly, and the solution turns clear. Alternating between hydrophobic domains in the protein are short sequences of amino acid residues that form the cross-linking domains (6). Coacervation may concentrate and align tropoelastin molecules prior to elastin formation via lysyl oxidase-mediated cross-linkage of the lysine residues that leads to a grow...

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Section: Properties Of Human Tropoelastinmentioning

confidence: 99%

Thermodynamic and Hydrodynamic Properties of Human Tropoelastin

Toonkool¹,

Regan²,

Kuchel³

et al. 2001

Journal of Biological Chemistry

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“…Soluble elastin is known to exhibit coacervation by a liquid-liquid phase separation. This coacervation is reversible by the effect of hydrophobic intermolecular interactions and the unique chemical structures of elastin [34,35]. The mixture solution of soluble elastin has only one coacervation temperature, which is the average value for all the molecules.…”

Section: Elastin Materials Using Soluble Elastin Isotypesmentioning

confidence: 99%

Creation of cross-linked electrospun isotypic-elastin fibers controlled cell-differentiation with new cross-linker

Miyamoto

Atarashi

Kadozono

et al. 2009

International Journal of Biological Macromolecules

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“…Elastin is a structural protein that helps to maintain the morphology of connective tissues [47][48][49]. At low temperatures, elastin is soluble in aqueous solutions.…”

Section: α-Elastin Characterizationmentioning

confidence: 99%