Evidence that Tropoelastin Exists as a Random Coil

Schein, Jay; Carpousis, Agamemnon J.; Rosenbloom, Joel

doi:10.1007/978-1-4684-9093-0_62

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…In electron micrographs, purified bovine and chick tropoelastin appeared spherical with a diameter of 5-7 nm (4, 40). Chick tropoelastin was interpreted as existing as a random coil with an s 20,w of 2.1 S as determined by sucrose density gradient centrifugation (41). This value is similar to the s 20,w 0 of Species 1 at both 20 and 37°C and together with electron micrographs of chick tropoelastin (4) suggest that Species 1 may adopt an expanded spherical form in solution.…”

Section: Properties Of Human Tropoelastinmentioning

confidence: 55%

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: 55%

Thermodynamic and Hydrodynamic Properties of Human Tropoelastin

Toonkool¹,

Regan²,

Kuchel³

et al. 2001

Journal of Biological Chemistry

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“…Disorder in this context is defined as the absence of extended b-structures and a-helices. Sedimentation velocity analyses of tropoelastin from chicken aortae suggest a random-coil conformation (Schein et al 1977). Sedimentation velocity analyses of tropoelastin from chicken aortae suggest a random-coil conformation (Schein et al 1977).…”

Section: Secondary Structure Of Elastin and Elastinlike Polypeptidesmentioning

confidence: 95%

“…Sedimentation velocity analyses of tropoelastin from chicken aorta indicate structural dimensions are best described in terms of an asymmetric rod and not a globular protein (Schein et al 1977). More recent analytical ultracentrifugation studies show recombinant human tropoelastin exists as a monomer in solution, with experimental data consistent with the presence of at least 2 species of equal concentration, which do not interconvert within 16 h (Toonkool et al 2001b).…”

Section: Tertiary Structure Flexibilitymentioning

confidence: 99%

Structural disorder and dynamics of elastinThis paper is one of a selection of papers published in this special issue entitled “Canadian Society of Biochemistry, Molecular & Cellular Biology 52nd Annual Meeting — Protein Folding: Principles and Diseases” and has undergone the Journal's usual peer review process.

Muiznieks

Weiss

Keeley

2010

Biochem. Cell Biol.

144

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Elastin is a self-assembling, extracellular-matrix protein that is the major provider of tissue elasticity. Here we review structural studies of elastin from over four decades, and draw together evidence for solution flexibility and conformational disorder that is inherent in all levels of structural organization. The characterization of disorder is consistent with an entropy-driven mechanism of elastic recoil. We conclude that conformational disorder is a constitutive feature of elastin structure and function.

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Elastin

Franzblau¹,

Faris²

1981

Cell Biology of Extracellular Matrix

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Evidence that Tropoelastin Exists as a Random Coil

Cited by 6 publications

References 31 publications

Thermodynamic and Hydrodynamic Properties of Human Tropoelastin

Thermodynamic and Hydrodynamic Properties of Human Tropoelastin

Elastin

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