Nanostructural features of a spider dragline silk as revealed by electron and X-ray diffraction studies

Trancik, Jessika E.; Czernuszka, Jan T.; Bell, Fraser I.; Viney, Christopher

doi:10.1016/j.polymer.2005.01.110

Cited by 64 publications

(57 citation statements)

References 33 publications

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“…4B). Iterations of glycine-alanine couplets and poly-alanine repeats are thought to form b-crystalline structures, which contribute to tensile strength (Warwicker, 1960;Hayashi et al, 1999;Fedič et al, 2003;Lawrence et al, 2004;Trancik et al, 2006). Craig (1997) hypothesized that webspinner silk contains crystallites based on sheering forces that occur during spinning.…”

Section: Amino Acid Sequencementioning

confidence: 99%

Characterization of silk spun by the embiopteran, Antipaluria urichi

Collin

Garb

Edgerly

et al. 2009

Insect Biochemistry and Molecular Biology

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Section: Amino Acid Sequencementioning

confidence: 99%

Characterization of silk spun by the embiopteran, Antipaluria urichi

Collin

Garb

Edgerly

et al. 2009

Insect Biochemistry and Molecular Biology

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“…Earlier studies have shown that the hydration level and solvent conditions such as ion content and pH play a role in the structure and mechanical properties of silk proteins (Dicko et al 2004;Rammensee et al 2008). For instance, a unique aspect of silk fibres is their capacity to exhibit a dramatic reduction in length upon hydration; a phenomenon known as supercontraction (Shao & Vollrath 1999;van Beek et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…The existence of 3 1 helices, and beta-turn or beta-spiral conformations has been suggested for the amorphous domains (Cunniff et al 1994;Thiel et al 1997;van Beek et al 2002;Lefevre et al 2007); however, no definite atomistic-level structural model has yet been reported. It is anticipated that novel statistical mechanics approaches (Porter et al 2005), experimental methods, such as X-ray diffraction and scattering (Riekel & Vollrath 2001;Trancik et al 2006), solidstate nuclear magnetic resonance (NMR; Simmons et al 1996;van Beek et al 1999;Holland et al 2008;Jenkins et al 2010) and Raman spectroscopy (Rousseau et al 2004(Rousseau et al , 2009Lefevre et al 2007), combined with pioneering multiscale atomistic-modelling methods such as those based on density functional theory (Porter & Vollrath 2008; or molecular dynamics (Brooks 1995;Ma & Nussinov 2006;Buehler et al 2008;, will provide more insight into the atomic resolution structure for complex materials such as spider silk. An earlier study of silk using replica exchange molecular dynamics (REMD; ) has yielded interesting results in comparison with experiments (Kummerlen et al 1996;van Beek et al 2002;Holland et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Nanostructure and molecular mechanics of spider dragline silk protein assemblies

Keten

Buehler

2010

J. R. Soc. Interface.

241

262

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Spider silk is a self-assembling biopolymer that outperforms most known materials in terms of its mechanical performance, despite its underlying weak chemical bonding based on H-bonds. While experimental studies have shown that the molecular structure of silk proteins has a direct influence on the stiffness, toughness and failure strength of silk, no molecular-level analysis of the nanostructure and associated mechanical properties of silk assemblies have been reported. Here, we report atomic-level structures of MaSp1 and MaSp2 proteins from the Nephila clavipes spider dragline silk sequence, obtained using replica exchange molecular dynamics, and subject these structures to mechanical loading for a detailed nanomechanical analysis. The structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly beta-sheet crystal domains, while disorderly regions are formed by glycine-rich repeats that consist of 3 1 -helix type structures and beta-turns. Our structural predictions are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content. Mechanical shearing simulations on selected structures illustrate that the nanoscale behaviour of silk protein assemblies is controlled by the distinctly different secondary structure content and hydrogen bonding in the crystalline and semi-amorphous regions. Both structural and mechanical characterization results show excellent agreement with available experimental evidence. Our findings set the stage for extensive atomistic investigations of silk, which may contribute towards an improved understanding of the source of the strength and toughness of this biological superfibre.

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“…It is anticipated that novel statistical mechanics approaches [46], empirical methods, such as X-ray diffraction and scattering [47,48], solid-state nuclear magnetic resonance (e.g., ssNMR) [32,[49][50][51] and Raman spectroscopy [23,25,52], combined with pioneering multiscale atomistic-modeling methods such as those based on Density Functional Theory (DFT) [29] or molecular dynamics [27], will provide more insight into the atomic resolution structure for complex materials such as spider silk.…”

Section: A Two-phase Protein Compositementioning

confidence: 99%

Unlocking Nature: Case Studies

Cranford

Buehler

2012

Biomateriomics

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Defining the materiome consists of linking material properties and function across multiple scales, from nano to macro. The key to "unlocking" Nature is not the replication of biological materials, but full understanding of the mechanisms and material interactions that result in system-level functionality. Here, we look at two biological materials in detail: silk and bone. Silk-a high-performance polymer-like fiber-can be thought of as two phases synergetically acting together. The H-bonded β-sheet nanocrystals provide strength and toughness, while disordered semi-amorphous domains imbue extensibility.The resulting hyperelastic stiffening behavior is critical to the flaw tolerance and robustness of a spider's web. Bone, in contrast, is a composite material made of relatively stiff mineral (hydroxyapatite) and compliant protein (tropocollagen) components. Bone achieves strength and toughness through a variety of mechanisms, including nanoconfinement, fibrillar sliding, and crack bridging. The general insights gained from the investigation of such systems can be applied a vast array of technological applications. As the poet said, 'Only God can make a tree', probably because it's so hard to figure out how to get the bark on.Woody Allen, American Film director, actor, screenwriter IntroductionWhat constitutes a materiomic investigation? From a general perspective, any study that elucidates any material behavior or property at any scale is, by definition, investigating the materiome. A complete materiomic investigation, however, generally goes further and attempts to link structure to behavior, bridge multiple scales, and translate mechanisms to function. As we have seen, the complexity and multiscale structure of biological materials require a balance of computational and experimental approaches. To illustrate, this chapter focuses on two well-researched material systems from Nature, from nano to macro: silk and bone. Purely synthetic systems are discussed further in Chap. 10: Synthesis and Design.The exceptional mechanical properties of both silk and bone have been extensively studied experimentally and in computational investigations, with new insights

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Nanostructural features of a spider dragline silk as revealed by electron and X-ray diffraction studies

Cited by 64 publications

References 33 publications

Characterization of silk spun by the embiopteran, Antipaluria urichi

Characterization of silk spun by the embiopteran, Antipaluria urichi

Nanostructure and molecular mechanics of spider dragline silk protein assemblies

Unlocking Nature: Case Studies

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