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Bioinspired Histidine?Zn²⁺ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

ABSTRACT: Natural biopolymeric materials often possess properties superior to their individual components. In mussel byssus, reversible histidine (His)-metal coordination is a key feature, which mediates higher-order self-assembly as well as self-healing. The byssus structure, thus, serves as an excellent natural blueprint for the development of self-healing biomimetic materials with reversibly tunable mechanical properties. Inspired by byssal threads, we bioengineered His-metal coordination sites into a heterodimeric coiled coil (CC). These CC-forming peptides serve as a noncovalent cross-link for poly(ethylene glycol)-based hydrogels and participate in the formation of higher-order assemblies via intermolecular His-metal coordination as a second cross-linking mode. Raman and circular dichroism spectroscopy revealed the presence of ?-helical, Zn²⁺ cross-linked aggregates. Using rheology, we demonstrate that the hydrogel is self-healing and that the addition of Zn²⁺ reversibly switches the hydrogel properties from viscoelastic to elastic. Importantly, using different Zn²⁺:His ratios allows for tuning the hydrogel relaxation time over nearly three orders of magnitude. This tunability is attributed to the progressive transformation of single CC cross-links into Zn²⁺ cross-linked aggregates; a process that is fully reversible upon addition of the metal chelator ethylenediaminetetraacetic acid. These findings reveal that His-metal coordination can be used as a versatile cross-linking mechanism for tuning the viscoelastic properties of biomimetic hydrogels.

SUBMITTER: Tunn I

PROVIDER: S-EPMC6477626 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Bioinspired Histidine⁻Zn<sup>2+</sup> Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

Tunn Isabell I Harrington Matthew J MJ Blank Kerstin G KG

Biomimetics (Basel, Switzerland) 20190318 1

Natural biopolymeric materials often possess properties superior to their individual components. In mussel byssus, reversible histidine (His)-metal coordination is a key feature, which mediates higher-order self-assembly as well as self-healing. The byssus structure, thus, serves as an excellent natural blueprint for the development of self-healing biomimetic materials with reversibly tunable mechanical properties. Inspired by byssal threads, we bioengineered His-metal coordination sites into a ...[more]

PMID: 31105210

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Project description:Herein we report how de novo designed peptides can be used to investigate whether the position of a metal site along a linear sequence that folds into a three-stranded α-helical coiled coil defines the physical properties of Cd(II) ions in either CdS(3) or CdS(3)O (O-being an exogenous water molecule) coordination environments. Peptides are presented that bind Cd(II) into two identical coordination sites that are located at different topological positions at the interior of these constructs. The peptide GRANDL16PenL19IL23PenL26I binds two Cd(II) as trigonal planar 3-coordinate CdS(3) structures whereas GRANDL12AL16CL26AL30C sequesters two Cd(II) as pseudotetrahedral 4-coordinate CdS(3)O structures. We demonstrate how for the first peptide, having a more rigid structure, the location of the identical binding sites along the linear sequence does not affect the physical properties of the two bound Cd(II). However, the sites are not completely independent as Cd(II) bound to one of the sites ((113)Cd NMR chemical shift of 681 ppm) is perturbed by the metalation state (apo or [Cd(pep)(Hpep)(2)](+) or [Cd(pep)(3)](-)) of the second center ((113)Cd NMR chemical shift of 686 ppm). GRANDL12AL16CL26AL30C shows a completely different behavior. The physical properties of the two bound Cd(II) ions indeed depend on the position of the metal center, having pK(a2) values for the equilibrium [Cd(pep)(Hpep)(2)](+) → [Cd(pep)(3)](-) + 2H(+) (corresponding to deprotonation and coordination of cysteine thiols) that range from 9.9 to 13.9. In addition, the L26AL30C site shows dynamic behavior, which is not observed for the L12AL16C site. These results indicate that for these systems one cannot simply assign a "4-coordinate structure" and assume certain physical properties for that site since important factors such as packing of the adjacent Leu, size of the intended cavity (endo vs exo) and location of the metal site play crucial roles in determining the final properties of the bound Cd(II).

Dataset Information

Bioinspired Histidine?Zn²⁺ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

Publications

Bioinspired Histidine⁻Zn<sup>2+</sup> Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

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Dataset Information

Bioinspired Histidine?Zn2+ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

Publications

Bioinspired Histidine⁻Zn<sup>2+</sup> Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

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Bioinspired Histidine?Zn²⁺ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels.