Conformational Transition of Regenerated Spider Silk in Water

2013 ◽  
Vol 796 ◽  
pp. 107-111
Author(s):  
Ye Mei Zhang ◽  
Zhi Juan Pan
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Spider Silk ◽  
Conformational Transition ◽  
Ph Value ◽  
Random Coil ◽  
Spider Dragline Silk ◽  
Turn Structure ◽  
Α Helix ◽  
Spider Silks

Spider silks have excellent mechanical properties, which can even compare with some high-performance synthetic materials. Although as reported, the impressive mechanical properties are closely related to the primary amino acid sequence, the conformation that molecular chains form is also an important determinant. In this paper, effects of solvent, pH value, temperature, centrifugation and concentrating on the secondary structure of regenerated Ornithoctonus huwenna spider dragline silk protein aqueous solution were investigated by circular dichroism. Spidroin solutions prepared from different LiBr solutions had a distinct combination of secondary structures. The increasing temperature and concentrating can promote the formation of β-sheet structure. While centrifugation was opposite, which elevate the content of β-turn structure. Circular dichroic spectra quantitatively verified an increased α-helix structure content but a decrease of random coil and β-turn structure content with the increasing of pH value.

scholarly journals Presence of β-Turn Structure in Recombinant Spider Silk Dissolved in Formic Acid Revealed with NMR

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 511
Author(s):  
Yu Suzuki ◽  
Takanori Higashi ◽  
Takahiro Yamamoto ◽  
Hideyasu Okamura ◽  
Takehiro K. Sato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Formic Acid ◽  
Spider Silk ◽  
Chemical Shifts ◽  
Repetitive Sequences ◽  
Silk Protein ◽  
Random Coil ◽  
Oh Groups ◽  
Spider Silk Protein ◽  
Turn Structure

Spider dragline silk is a biopolymer with excellent mechanical properties. The development of recombinant spider silk protein (RSP)-based materials with these properties is desirable. Formic acid (FA) is a spinning solvent for regenerated Bombyx mori silk fiber with excellent mechanical properties. To use FA as a spinning solvent for RSP with the sequence of major ampullate spider silk protein from Araneus diadematus, we determined the conformation of RSP in FA using solution NMR to determine the role of FA as a spinning solvent. We assigned 1H, 13C, and 15N chemical shifts to 32-residue repetitive sequences, including polyAla and Gly-rich regions of RSP. Chemical shift evaluation revealed that RSP is in mainly random coil conformation with partially type II β-turn structure in the Gly-Pro-Gly-X motifs of the Gly-rich region in FA, which was confirmed by the 15N NOE data. In addition, formylation at the Ser OH groups occurred in FA. Furthermore, we evaluated the conformation of the as-cast film of RSP dissolved in FA using solid-state NMR and found that β-sheet structure was predominantly formed.

Phospholipids modulate the biophysical properties and vasoactivity of PACAP-(1—38)

2002 ◽  
Vol 93 (4) ◽  
pp. 1377-1383 ◽  
Author(s):  
Takaya Tsueshita ◽  
Salil Gandhi ◽  
Hayat Önyüksel ◽  
Israel Rubinstein
Keyword(s):  
Conformational Transition ◽  
Critical Micellar Concentration ◽  
Random Coil ◽  
Cheek Pouch ◽  
Hamster Cheek Pouch ◽  
Pituitary Adenylate Cyclase ◽  
Peripheral Microcirculation ◽  
Α Helix

The purpose of this study was to elucidate the interactions between pituitary adenylate cyclase-activating peptide (PACAP)-(1—38) and phospholipids in vitro and to determine whether these phenomena modulate, in part, the vasorelaxant effects of the peptide in the intact peripheral microcirculation. We found that the critical micellar concentration of PACAP-(1—38) was 0.4–0.9 μM. PACAP-(1—38) significantly increased the surface tension of a dipalmitoylphosphatidylcholine monolayer and underwent conformational transition from predominantly random coil in saline to α-helix in the presence of distearoyl-phosphatidylethanolamine-polyethylene glycol (molecular mass of 2,000 Da) sterically stabilized phospholipid micelles (SSM) ( P < 0.05). Using intravital microscopy, we found that aqueous PACAP-(1—38) evoked significant concentration-dependent vasodilation in the intact hamster cheek pouch that was significantly potentiated when PACAP-(1—38) was associated with SSM ( P < 0.05). The vasorelaxant effects of aqueous PACAP-(1—38) were mediated predominantly by PACAP type 1 (PAC1) receptors, whereas those of PACAP-(1—38) in SSM predominantly by PACAP/vasoactive intestinal peptide type 1 and 2 (VPAC1/VPAC2) receptors. Collectively, these data indicate that PACAP-(1—38) self-associates and interacts avidly with phospholipids in vitro and that these phenomena amplify peptide vasoactivity in the intact peripheral microcirculation.

scholarly journals Tensegrity Modelling and the High Toughness of Spider Dragline Silk

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1510
Author(s):  
Fernando Fraternali ◽  
Nicola Stehling ◽  
Ada Amendola ◽  
Bryan Andres Tiban Anrango ◽  
Chris Holland ◽  
...  
Keyword(s):  
Spider Silk ◽  
Low Voltage ◽  
Microstructural Characterization ◽  
Hierarchical Organization ◽  
Air Plasma ◽  
Poisson Effect ◽  
Dragline Silk ◽  
Spider Dragline Silk ◽  
A Chain ◽  
Spider Silks

This work establishes a tensegrity model of spider dragline silk. Tensegrity systems are ubiquitous in nature, being able to capture the mechanics of biological shapes through simple and effective modes of deformation via extension and contraction. Guided by quantitative microstructural characterization via air plasma etching and low voltage scanning electron microscopy, we report that this model is able to capture experimentally observed phenomena such as the Poisson effect, tensile stress-strain response, and fibre toughness. This is achieved by accounting for spider silks’ hierarchical organization into microfibrils with radially variable properties. Each fibril is described as a chain of polypeptide tensegrity units formed by crystalline granules operating under compression, which are connected to each other by amorphous links acting under tension. Our results demonstrate, for the first time, that a radial variability in the ductility of tensegrity chains is responsible for high fibre toughness, a defining and desirable feature of spider silk. Based on this model, a discussion about the use of graded tensegrity structures for the optimal design of next-generation biomimetic fibres is presented.

scholarly journals High-performance spider webs: integrating biomechanics, ecology and behaviour

2010 ◽  
Vol 8 (57) ◽  
pp. 457-471 ◽  
Author(s):  
Aaron M. T. Harmer ◽  
Todd A. Blackledge ◽  
Joshua S. Madin ◽  
Marie E. Herberstein
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Spider Webs ◽  
Spider Dragline Silk ◽  
Spider Web ◽  
Web Spider ◽  
Species Invasions ◽  
Synthetic Materials ◽  
Orb Web ◽  
Spider Silks

Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks.

Raman Spectroscopic Investigation of the Denaturation Process of Silk Fibroin

1989 ◽  
Vol 43 (7) ◽  
pp. 1269-1272 ◽  
Author(s):  
Siding Zheng ◽  
Guanxian Li ◽  
Wenhuo Yao ◽  
Tongyin Yu
Keyword(s):  
Raman Spectroscopy ◽  
Silk Fibroin ◽  
Conformational Transition ◽  
Transition Process ◽  
Random Coil ◽  
Helical Conformation ◽  
Extension Rate ◽  
Α Helix ◽  
Β Sheet ◽  
Denaturation Process

The mechanical denaturation process of silk fibroin is examined by Raman spectroscopy. The fresh silk fibroins from the middle gland of mature silkworms are drawn to various ratios on a tensile tester ( R = ldrawn/ linitial, where l is length) and their conformations are measured with Raman spectroscopy. Undrawn silk fibroin is mainly in the random coil structure with some α-helical conformation, the characteristic bands appearing at 1252 and 1660 (random coil) and at 942, 1106, and 1270 cm−1 (α-helix). When the samples are drawn up to R = 4 at an extension rate of 500 mm/min, two peaks at 1233 cm−1 (the amide III band) and 1085 cm−1 appear; it is shown that the β-sheet conformation is then formed. With an increase in drawing ratios, the intensities of these β-sheet bands increase and those of the random coil and α-helical bands decrease gradually. These changes indicate that, under the action of stress, the conformation of fibroin is altered from random coil and α-helix to β-sheet structures. This result is quite similar to the results achieved by the spinning of the silkworm. The effect of the water content in liquid silk on this conformational transition process is revealed and discussed.

scholarly journals Post-secretion processing influences spider silk performance

2012 ◽  
Vol 9 (75) ◽  
pp. 2479-2487 ◽  
Author(s):  
Sean J. Blamires ◽  
Chung-Lin Wu ◽  
Todd A. Blackledge ◽  
I-Min Tso
Keyword(s):  
Mechanical Properties ◽  
Amino Acid ◽  
Ground State ◽  
Spider Silk ◽  
Mechanical Performance ◽  
Protein Composition ◽  
Compositional Changes ◽  
Spinning Speed ◽  
Spider Silks ◽  
Β Sheet

Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins—MaSp1 predominately contains alanine and glycine and forms strength enhancing β-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We predicted that post-secretion processing causes variation in the mechanical performance of wild MA silk independent of protein composition or spinning speed across 10 species of spider. We used supercontraction to remove post-secretion effects and compared the mechanics of silk in this ‘ground state’ with wild native silks. Native silk mechanics varied less among species compared with ‘ground state’ silks. Variability in the mechanics of ‘ground state’ silks was associated with proline composition. However, variability in native silks did not. We attribute interspecific similarities in the mechanical properties of native silks, regardless of amino acid compositions, to glandular processes altering molecular alignment of the proteins prior to extrusion. Such post-secretion processing may enable MA silk to maintain functionality across environments, facilitating its function as a component of an insect-catching web.

scholarly journals Basic Principles in the Design of Spider Silk Fibers

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1794
Author(s):  
José Pérez-Rigueiro ◽  
Manuel Elices ◽  
Gustavo R. Plaza ◽  
Gustavo V. Guinea
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Spider Silk ◽  
Design Principles ◽  
Tensile Behavior ◽  
Original Design ◽  
Basic Principles ◽  
Silk Fibers ◽  
The Relationship ◽  
Selection Of

The prominence of spider silk as a hallmark in biomimetics relies not only on its unrivalled mechanical properties, but also on how these properties are the result of a set of original design principles. In this sense, the study of spider silk summarizes most of the main topics relevant to the field and, consequently, offers a nice example on how these topics could be considered in other biomimetic systems. This review is intended to present a selection of some of the essential design principles that underlie the singular microstructure of major ampullate gland silk, as well as to show how the interplay between them leads to the outstanding tensile behavior of spider silk. Following this rationale, the mechanical behavior of the material is analyzed in detail and connected with its main microstructural features, specifically with those derived from the semicrystalline organization of the fibers. Establishing the relationship between mechanical properties and microstructure in spider silk not only offers a vivid image of the paths explored by nature in the search for high performance materials, but is also a valuable guide for the development of new artificial fibers inspired in their natural counterparts.

scholarly journals Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1013 ◽  
Author(s):  
Hsuan-Chen Wu ◽  
Aditi Pandey ◽  
Liang-Yu Chang ◽  
Chieh-Yun Hsu ◽  
Thomas Chung-Kuang Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Spider Silk ◽  
Post Treatment ◽  
Molecular Structures ◽  
Random Coil ◽  
Silk Fibers ◽  
Physical Strength ◽  
Β Sheet ◽  
Post Treatment Process

The superlative mechanical properties of spider silk and its conspicuous variations have instigated significant interest over the past few years. However, current attempts to synthetically spin spider silk fibers often yield an inferior physical performance, owing to the improper molecular interactions of silk proteins. Considering this, herein, a post-treatment process to reorganize molecular structures and improve the physical strength of spider silk is reported. The major ampullate dragline silk from Nephila pilipes with a high β-sheet content and an adequate tensile strength was utilized as the study material, while that from Cyrtophora moluccensis was regarded as a reference. Our results indicated that the hydrothermal post-treatment (50–70 °C) of natural spider silk could effectively induce the alternation of secondary structures (random coil to β-sheet) and increase the overall tensile strength of the silk. Such advantageous post-treatment strategy when applied to regenerated spider silk also leads to an increment in the strength by ~2.5–3.0 folds, recapitulating ~90% of the strength of native spider silk. Overall, this study provides a facile and effective post-spinning means for enhancing the molecular structures and mechanical properties of as-spun silk threads, both natural and regenerated.

scholarly journals Expanding Canonical Spider Silk Properties through a DNA Combinatorial Approach

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3596
Author(s):  
Zaroug Jaleel ◽  
Shun Zhou ◽  
Zaira Martín-Moldes ◽  
Lauren M. Baugh ◽  
Jonathan Yeh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Recombinant Proteins ◽  
Elastic Moduli ◽  
Spider Silk ◽  
Building Blocks ◽  
Random Coil ◽  
Infrared Spectrometry ◽  
Silk Proteins ◽  
Dragline Silk ◽  
Latrodectus Hesperus

The properties of native spider silk vary within and across species due to the presence of different genes containing conserved repetitive core domains encoding a variety of silk proteins. Previous studies seeking to understand the function and material properties of these domains focused primarily on the analysis of dragline silk proteins, MaSp1 and MaSp2. Our work seeks to broaden the mechanical properties of silk-based biomaterials by establishing two libraries containing genes from the repetitive core region of the native Latrodectus hesperus silk genome (Library A: genes masp1, masp2, tusp1, acsp1; Library B: genes acsp1, pysp1, misp1, flag). The expressed and purified proteins were analyzed through Fourier Transform Infrared Spectrometry (FTIR). Some of these new proteins revealed a higher portion of β-sheet content in recombinant proteins produced from gene constructs containing a combination of masp1/masp2 and acsp1/tusp1 genes than recombinant proteins which consisted solely of dragline silk genes (Library A). A higher portion of β-turn and random coil content was identified in recombinant proteins from pysp1 and flag genes (Library B). Mechanical characterization of selected proteins purified from Library A and Library B formed into films was assessed by Atomic Force Microscopy (AFM) and suggested Library A recombinant proteins had higher elastic moduli when compared to Library B recombinant proteins. Both libraries had higher elastic moduli when compared to native spider silk proteins. The preliminary approach demonstrated here suggests that repetitive core regions of the aforementioned genes can be used as building blocks for new silk-based biomaterials with varying mechanical properties.

EFFECT OF STORAGE TIME AND CONCENTRATION ON STRUCTURE OF REGENERATED SILK FIBROIN SOLUTION

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3878-3883 ◽  
Author(s):  
FANG XIE ◽  
HUILI SHAO ◽  
XUECHAO HU
Keyword(s):  
Aqueous Solution ◽  
Silk Fibroin ◽  
Storage Time ◽  
Conformational Transition ◽  
Solution Concentration ◽  
Cd Spectroscopy ◽  
Random Coil ◽  
Conformational Transformation ◽  
Regenerated Silk Fibroin ◽  
Α Helix

Concentrated regenerated silk fibroin (RSF) aqueous solutions with concentration close to that of the native silk fibroin (15.5%, 25.5% and 31%) were prepared. The effect of storage time and concentration on the conformational transition of the concentrated RSF aqueous solution was studied by Raman spectroscopy and circular dichroism (CD) spectroscopy. At the same time, the conformational change of RSF aqueous solution in flowing state was also investigated. It was found that the conformation of silk fibroin was changed gradually from random coil/α-helix to β-sheet structure during the storage. And the conformational transformation was accelerated with the increasing of the RSF aqueous solution concentration. When the solution was in flowing state, the conformational transformation was also accelerated.

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