Silk I and Silk II studied by fast scanning calorimetry

Cebe, Peggy; Partlow, Benjamin P.; Kaplan, David L.; Wurm, Andreas; Zhuravlev, Evgeny; Schick, Christoph

doi:10.1016/j.actbio.2017.04.001

Cited by 100 publications

(79 citation statements)

References 51 publications

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“…The amide I band at 1580-1720 cm −1 was used for a peak deconvolution analysis ( Figure 5A). According to previous reports, the deconvolution peak in the wave number range of 1615-1645 cm −1 and 1690-1700 cm −1 represent β-sheet structure, 1645-1665 cm −1 represents α-helix/random coils structure, 1680-1690 cm −1 represents β-turn structure [24][25][26][27][28][29]. The composition of secondary structures of the silk fibers differed between the transgenic and wild-type lines ( Figure 5A).…”

Section: Secondary Structural and Crystal Morphological Characteristisupporting

confidence: 59%

Effects of Osiris9a on Silk Properties in Bombyx mori Determined by Transgenic Overexpression

Cheng

Zhang

Peng

et al. 2020

IJMS

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Osiris is an insect-specific gene family with multiple biological roles in development, phenotypic polymorphism, and protection. In the silkworm, we have previously identified twenty-five Osiris genes with high evolutionary conservation and remarkable synteny among several insects. Bombxy mori Osiris9a (BmOsi9a) is expressed only in the silk gland, particularly in the middle silk gland (MSG). However, the biological function of BmOsi9a is still unknown. In this study, we overexpressed BmOsi9a in the silk gland by germline transgene expression. BmOsi9a was overexpressed not only in the MSG but also in the posterior silk gland (PSG). Interestingly, BmOsi9a could be secreted into the lumen in the MSG but not in the PSG. In the silk fiber, overexpressed BmOsi9a interacted with Sericin1 in the MSG, as confirmed by a co-immunoprecipitation assay. The overexpression of BmOsi9a altered the secondary structure and crystallinity of the silk fiber, thereby changing the mechanical properties. These results provide insight into the mechanisms underlying silk proteins secretion and silk fiber formation.

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Section: Secondary Structural and Crystal Morphological Characteristisupporting

confidence: 59%

Effects of Osiris9a on Silk Properties in Bombyx mori Determined by Transgenic Overexpression

Cheng

Zhang

Peng

et al. 2020

IJMS

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“…[111] While β-sheet crystal melt cannot be distinguished from protein degradation in DSC analysis, FSC run at a rate of 2000 K/s has been shown to overcome this limitation. The relatively short resonance time at which the high temperatures are held in FSC limits protein degradation, allowing crystal melting and glass transition to be observed.…”

Section: Thermal Analysismentioning

confidence: 99%

“…[110] In another example, silk I and silk II crystals in silk fibroin films were studied by FSC, and results revealed that the crystals had distinct melting temperatures (T m (Silk I) = 292 ± 3.8°C, T m (Silk II) = 351 ± 2.6°C) (Figure 10). [111] FSC requires thin (<10 µm) film samples to work with the fast heating rates. [112] Limitations associated with FSC include significant data processing, and an open experimental setup where heat is lost throughout the process.…”

Section: Thermal Analysismentioning

confidence: 99%

Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

McGill

Holland

Kaplan

2018

Macromol. Rapid Commun.

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Silk proteins are biopolymers produced by spinning organisms that have been studied extensively for applications in materials engineering, regenerative medicine, and devices due to their high tensile strength and extensibility. This remarkable combination of mechanical properties arises from their unique semi-crystalline secondary structure and block copolymer features. The secondary structure of silks is highly sensitive to processing, and can be manipulated to achieve a wide array of material profiles. Studying the secondary structure of silks is therefore critical to understanding the relationship between structure and function, the strength and stability of silk-based materials, and the natural fiber synthesis process employed by spinning organisms. However, silks present unique challenges to structural characterization due to high-molecular-weight protein chains, repetitive sequences, and heterogeneity in intra- and interchain domain sizes. Here, experimental techniques used to study the secondary structure of silks, the information attainable from these techniques, and the limitations associated with them are reviewed. Ultimately, the appropriate utilization of a suite of techniques discussed here will enable detailed characterization of silk-based materials, from studying fundamental processing-structure-function relationships to developing commercially useful quality control assessments.

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“…Silks have been subjected to calorimetric tests for over 20 years but with the focus either on natural spun fibers (which are not directly relevant in the context of this work) or artificial silk feedstocks/films, where processing has altered the state of hydration so much that these artificial silks may no longer represent a native unspun silk protein/model aquamelt . However, in the early 2000s, Tanaka et al.…”

Section: Introductionmentioning

confidence: 99%

Differential Scanning Calorimetry of Native Silk Feedstock

Holland

Hawkins²,

Frydrych³

et al. 2018

Macromolecular Bioscience

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Native silk proteins, extracted directly from the silk gland prior to spinning, offer access to a naturally hydrated protein that has undergone little to no processing. Combined with differential scanning calorimetry (DSC), it is possible to probe the thermal stability and hydration status of silk and thus investigate its denaturation and solidification, echoing that of the natural spinning process. It is found that native silk is stable between −10 °C and 55 °C, and both the high‐temperature enthalpy of denaturation (measured via modulated temperature DSC) and a newly reported low‐temperature ice‐melting transition may serve as useful quality indicators in the future for artificial silks. Finally, compared to albumin, silk's denaturation enthalpy is much lower than expected, which is interpreted within a recently proposed entropic desolvation framework which can serve to unveil the low‐energy aquamelt processing pathway.

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Silk I and Silk II studied by fast scanning calorimetry

Cited by 100 publications

References 51 publications

Effects of Osiris9a on Silk Properties in Bombyx mori Determined by Transgenic Overexpression

Effects of Osiris9a on Silk Properties in Bombyx mori Determined by Transgenic Overexpression

Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

Differential Scanning Calorimetry of Native Silk Feedstock

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