Pressure Sensitive Adhesion of an Elastomeric Protein Complex Extracted From Squid Ring Teeth

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

Saadat

et al. 2016

Self Cite

113

Many globular and structural proteins have repetitions in their sequences or structures. However, a clear relationship between these repeats and their contribution to the mechanical properties remains elusive. We propose a new approach for the design and production of synthetic polypeptides that comprise one or more tandem copies of a single unit with distinct amorphous and ordered regions. Our designed sequences are based on a structural protein produced in squid suction cups that has a segmented copolymer structure with amorphous and crystalline domains. We produced segmented polypeptides with varying repeat number, while keeping the lengths and compositions of the amorphous and crystalline regions fixed. We showed that mechanical properties of these synthetic proteins could be tuned by modulating their molecular weights. Specifically, the toughness and extensibility of synthetic polypeptides increase as a function of the number of tandem repeats. This result suggests that the repetitions in native squid proteins could have a genetic advantage for increased toughness and flexibility.tandem repeat | high strength | protein | thermoplastic | squid ring teeth P roteins are heteropolymers that provide a variety of building blocks for designing biological materials (1). Proteins have several advantages as natural materials: (i) their chain length, sequence, and stereochemistry can be easily controlled, (ii) the molecular structure of proteins is well-defined (e.g., secondary, tertiary, and quaternary structures), (iii) they provide a variety of functional chemistries for conjugation to other biomolecules or polymers, and (iv) they can be designed to exhibit a variety of physical properties (2). Proteins are diverse but often display substantial similarity in sequence and 3D structure. Duplication of structural units is a natural evolutionary strategy for increasing the complexity of both globular and fibrous/ structural proteins (3). For example, collagen has polyproline-and glycine-rich helices, whereas silk and elastin have β-spiral [GPGXX], linker [GP(S,Y,G)], and 3 10 -helix [GGX] repeats. These repetitions are advantageous because of the intrinsic promotion of stability through the periodic recurrence of favorable interactions (4-7).A new family of repetitive structural proteins was recently identified in the tentacles of several squid species (8, 9). Squid have teeth-like structures inside their suckers that allow the animals to grip tightly on a diverse array of objects (10). Using the tools of molecular biology and proteomics, it has been shown that these squid ring teeth (SRT) proteins have segmented semicrystalline morphology with repetitive amorphous and crystalline domains. SRT-based materials were shown to have high elastic modulus: 4-8 GPa in air and 2-4 GPa underwater below the glass transition temperature (11). However, a clear relationship between the molecular structure and the mechanical properties of this material remains elusive. This problem is complex, because SRT proteins are polydispersed i...

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Molecular tandem repeat strategy for elucidating mechanical properties of high-strength proteins

Jung

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

Saadat

et al. 2016

Self Cite

113

“…Native SRT (16) and silk (17) proteins were extracted from the tentacles of Loligo vulgaris and cocoons of Bombyx mori respectively following the protocol reported earlier. The proteins were dissolved in organic solvents and processed for deposition of pure polymeric protein films as described in Methods section.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast Laser-Probing Spectrocopy for Studying Molecular Structure of Polymeric Proteins

Jung

Szwejkowski

et al. 2016

Preprint

Self Cite

We report the development of a new technique to screen protein crystallinity quantitatively based on laser-probing spectroscopy with sub-picosecond resolution. First, we show theoretically that the temperature dependence of the refractive index of a polymeric protein is correlated to its crystallinity. Then, we performed time-domain thermo-transmission experiments on purified semi-crystalline proteins, both native and recombinant (i.e., silk and squid ring teeth), and also on intact E. coli cells bearing overexpressed recombinant protein. Our results demonstrate, for the first time, quantification of crystallinity in real time for polymeric proteins. Our approach can potentially be used for screening an ultra-large number of polymeric proteins in vivo. peer-reviewed)

“…The rings are composed of a group of repetitive proteins, ranging from 15 to 60 kDa, which have a segmented sequence topology similar to semi-crystalline segmented copolymers (22,23). The repetitive sequence favors the formation of a beta-sheet-rich cross-links that confers unique mechanical (24), adhesive (25), thermal (26), optical (27), and self-healing (28) properties to SRT. Furthermore, SRT is easily processed by solution and thermal fabrication methods into nano to macro protein-based materials, from nanotubes and nanoparticles to large-scale objects (25).…”

Section: Introductionmentioning

confidence: 99%

Squid Ring Teeth Coated Mesh Improves Abdominal Wall Repair

Leberfinger

Hospodiuk

et al. 2017

Preprint

Self Cite