Absorption spectroscopy and binding constants for first-row transition metal complexes of a DOPA-containing peptide

Sever, Mary J.; Wilker, Jonathan J.

doi:10.1039/b509586g

Cited by 95 publications

(109 citation statements)

References 44 publications

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“…The initially green solution turned blue and finally red as the catechol-Fe 3þ stoichiometry changed from mono-to bis-to tris-, respectively. Identical shifts in absorbance have been reported elsewhere (17). The relative fractions of the three coordination states, extracted from the absorbance data (see Methods for details), show that the monospecies dominate at pH < 5.6, bisat 5.6 < pH < 9.1, and tris-at pH > 9.1 (Fig.…”

Section: Resultsmentioning

confidence: 99%

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Holten‐Andersen

Harrington

Birkedal

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

1,413

1,326

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Growing evidence supports a critical role of metal-ligand coordination in many attributes of biological materials including adhesion, self-assembly, toughness, and hardness without mineralization [Rubin DJ, Miserez A, Waite JH (2010) Advances in Insect Physiology: Insect Integument and Color, eds Jérôme C, Stephen JS (Academic Press, London), pp . Coordination between Fe and catechol ligands has recently been correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and proposed to endow self-healing properties [Harrington MJ, Masic A, HoltenAndersen N, Waite JH, Fratzl P (2010) Science 328:216-220]. Inspired by the pH jump experienced by proteins during maturation of a mussel byssus secretion, we have developed a simple method to control catechol-Fe 3þ interpolymer cross-linking via pH. The resonance Raman signature of catechol-Fe 3þ cross-linked polymer gels at high pH was similar to that from native mussel thread cuticle and the gels displayed elastic moduli (G′) that approach covalently cross-linked gels as well as self-healing properties.biomaterials | catecholate polymer | metal coordination | reversible cross-links | physical gels M ussel byssal threads are protected against wear by a cuticle, an outer proteinaceous coating, that despite a hardness of ∼0.1 GPa, accommodates large cyclic strains in the turbulent intertidal zone (1, 2). During strain, the cuticle suppresses macroscale failure by limiting crack propagation to the microscale (1, 3). It was recently demonstrated that a small amount of Fe (<1 wt%) plays an important role in this mechanism; bonding with the catechol-like amino acid dihydroxy-phenylalanine (dopa) in the cuticle protein, mfp-1 (4-6). Tris-and bis-catecholFe 3þ complexes possess some of the highest known stability constants of metal-ligand chelates (log K S ≈ 37-40, where K S is the equilibrium constant for the complex formation) (7-10) and single molecule tensile tests have demonstrated that the breaking of a metal-dopa bond requires a force only modestly lower than the force required to rupture a covalent bond under identical loading conditions (∼0.8 nN vs. ∼2 nN, respectively) (11). Harrington et al. proposed a model where the catecholFe 3þ complexes in the cuticle function as sacrificial load-bearing cross-links facilitating extensibility of the material (4). In contrast to covalent bonds, metal-dopa bonds can spontaneously reform after breaking (11) and the model predicts that the damage accumulated in the cuticle could self-heal via reformation of broken catechol-Fe 3þ complexes (4). Here we describe a strategy for introducing bis-and/or tris-catechol-Fe 3þ cross-links into a synthetic polymer network and demonstrate that such a network indeed displays high elastic moduli and self-healing properties. ResultsThe stoichiometry of catechol-Fe 3þ complexes (mono-, bis-, or tris-) is controlled by pH via the deprotonation of the catechol hydroxyls (Fig. 1A). The pH required to establish the bis-and tris-complexes is typically reported to be above pH...

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Section: Resultsmentioning

confidence: 99%

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Holten‐Andersen

Harrington

Birkedal

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

1,413

1,326

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“…[19,20] Later on, taking advantage of this strong affinity, catechol derivatives have been widely used for synthesis of Ti IV complexes and even as binding agents for TiO 2 nanoparticles. [21][22][23][24] In this paper, we describe the synthesis of a new ligand H 6 4, which bears a catechol and a diethylenetriaminepentaacetic acid (DTPA) moiety linked together through an amide bond (Scheme 1). The DTPA unit provides a stable chelating environment for Ln…”

Section: A C H T U N G T R E N N U N G (H 2 O) 3 ]mentioning

confidence: 99%

A Self‐Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent

Dehaen

Eliseeva

Kimpe

et al. 2011

Chemistry A European J

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A ditopic chelating ligand (H(6)4) that bears catechol and diethylenetriamine-N,N,N',N'',N''-pentaacetate (DTPA) has been designed and shown to specifically bind lanthanide(III) ions at the DTPA core ([Ln(H(2)4)(H(2)O)](-)) and further self-assemble with titanium(IV), thereby giving rise to the formation of a supramolecular metallostar complex with a lanthanide(III)-to-titanium(IV) ratio of 3:1, [(Ln4)(3)Ti(H(2)O)(3)](5-) (Ln=La, Eu, Gd). The efficacy of the metallostar complex as a potential bimodal optical/magnetic resonance imaging (MRI) agent has been evaluated. Nuclear magnetic relaxation dispersion (NMRD) measurements for the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex have demonstrated an enhanced r(1) relaxivity that corresponds to 36.9 s(-1) mM(-1) per metallostar molecule at 20 MHz and 310 K, which is a result of a decreased tumbling rate. The ability of the complex to bind to human serum albumin (HSA) was also examined by relaxometric measurements. In addition, upon UV irradiation the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex exhibits broad-band green emission in the range 400-750 nm with a maximum at 490 nm. Taking into account the high relaxivity and luminescence properties, the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex is a good lead compound for the development of efficient bimodal contrast agents.

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“…We have shown that Fe 3þ binding to DOPA-containing peptides is pH dependent, with binding beginning in acidic solutions, with Fe(peptide) formation observed at pH % 3.5. [16] More basic conditions facilitate greater metal-peptide interactions, with Fe(peptide) 3 forming above pH % 7.5. [16] However, our work with whole protein (molecular weight %100 000) has shown that such metal-DOPA interactions occur more readily, regardless of pH.…”

Section: Experimental Partmentioning

confidence: 99%

Structural Effects of Crosslinking a Biopolymer Hydrogel Derived from Marine Mussel Adhesive Protein

Loizou

Weisser

Dundigalla

et al. 2006

Macromolecular Bioscience

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In an effort to explore new biocompatible substrates for biomedical technologies, we present a structural study on a crosslinked gelatinous protein extracted from marine mussels. Prior studies have shown the importance of iron in protein crosslinking and mussel adhesive formation. Here, the structure and properties of an extracted material were examined both before and after crosslinking with iron. The structures of these protein hydrogels were studied by SEM, SANS, and SAXS. Viscoelasticity was tested by rheological means. The starting gel was found to have a heterogeneous porous structure on a micrometer scale and, surprisingly, a regular structure on the micron to nanometer scale. However disorder, or "no periodic structure", was deduced from scattering on nanometer length scales at very high q. Crosslinking with iron condensed the structure on a micrometer level. On nanometer length scales at high q, small angle neutron scattering showed no significant differences between the samples, possibly due to strong heterogeneity. X-ray scattering also confirmed the absence of any defined periodic structure. Partial crosslinking transformed the viscoelastic starting gel into one with more rigid and elastic properties.

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Absorption spectroscopy and binding constants for first-row transition metal complexes of a DOPA-containing peptide

Cited by 95 publications

References 44 publications

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

A Self‐Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent

Structural Effects of Crosslinking a Biopolymer Hydrogel Derived from Marine Mussel Adhesive Protein

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