Some of the proline gets converted to hydroxy proline during the post-translational modification process. On the other hand, MaSp2 contains proline (P)-rich pentapeptide sequences such as GPGQQ and GPGGX (where X = A, serine (S) or Y). cDNA analyses of MA glands of orb-weaving spiders reveal that MaSp1 contains glycine (G)-rich tripeptide sequences such as GGX and GXG (where X = glutamine (Q), tyrosine (Y), leucine (L) or arginine (R)), and consecutive polyalanine (A) motifs. darwini incorporates a novel MaSp4 (major ampullate spidroin 4) with MaSp1 (major ampullate spidroin 1) and MaSp2 (major ampullate spidroin 2), which are typically found in the dragline silk from other orb-weaving spider species. darwini dragline silk is essential not only for elucidating the evolutionary root of its foraging strategy but also for designing biomaterials with exceptional mechanical properties. Understanding the molecular origin of the exceptionally high toughness of C. darwini (350 ± 93 MPa) surpasses by two to three times any other previously investigated dragline silk (10–230 MPa). To our knowledge, the toughness of the dragline silk of C. In 2010, a new species, Darwin's bark spider ( Caerostris darwini), was described, which builds the largest known orb webs across ponds and rivers in Madagascar (web area up to 2.8 m 2 and bridgelines up to 25 m). Generally, spider MA silk outperforms high-energy absorbing synthetic polymers such as Kevlar by approximately 300% on a volume-to-volume comparison. The high toughness allows MA silk to absorb the tremendous kinetic energy of flying insects when they hit the web. The dragline or major ampullate (MA) silk produced by orb-weaving spiders is used as a lifeline and as supporting radii for the capture silk in webs and possesses excellent tensile strength, elasticity and the ability to absorb energy before reaching breaking point. Our study highlights that additional information including crystal size and crystal and chain orientation is necessary to build a complete structure–property correlation model. However, after supercontraction, only modulus and strain at break correlate with percentages of β-sheets and β-turns. Before supercontraction, toughness, modulus and tensile strength correlate with percentages of β-sheets, unordered or random coiled regions and β-turns. darwini MA silk possesses a unique protein composition with a lower ratio of helices (31%) and β-sheets (20%) than other species. darwini and four other spider species with mechanical properties before and after supercontraction to understand the effect of the additional MaSp4 protein.
Here, we correlate the relative protein secondary structure composition of MA silk from C. However, no direct correlation has been made between the silk's molecular structure and its mechanical properties for C.
darwini MA silk's extraordinary toughness. Previous research suggests that a unique MaSp4 protein incorporates proline into a novel glycine–proline–glycine–proline motif and may explain C. The MA silk from Darwin's bark spider ( Caerostris darwini) is estimated to be two to three times tougher than the MA silk from other spider species. The spider major ampullate (MA) silk exhibits high tensile strength and extensibility and is typically a blend of MaSp1 and MaSp2 proteins with the latter comprising glycine–proline–glycine–glycine-X repeating motifs that promote extensibility and supercontraction.
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