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邵正中, Jinrong Yao, Dahui Xiao, Xin Chen, Ping Zhou, Tongyin Yu, and Zhengzhong Shao *
Macromolecules 2003, 36, 7508-7512,-0001,():
-1年11月30日
With the step-growth polymerization of bis (oligopeptides) and diisocyanates, two silkproteinlike multiblock polymers (P1, P2), containing-(Ala)4-and-(GlyAlaGlyAla)-sequence derived from the crystalline region of spider dragline silk and silkworm (Bombyx mori) silk respectively, has been synthesized successfully. The intrinsic viscosities of P1 and P2 measured in dichloroacetic acid at 25℃ were 0.31 and 0.26dL/g. FT-IR, 13C CP/MAS NMR and WAXD measurements revealed the oligopeptide segments in these multiblock polymers could aggregate spontaneously into β-sheet structure in solid state. In addition, it was also found there were non-β-sheet structures in the synthetic polymers, which indicated such polymers had a solid-state structure similar to that of natural silks.
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【期刊论文】The effect of solvents on the contraction and mechanical properties of spider silk
邵正中, Zhengzhong Shao, Fritz Vollrath *
Polymer 40(1999)1799-1806,-0001,():
-1年11月30日
We examined the mechanical characteristics of four major ampullate (MA) dragline silks during and after submersion in a range of solvents. The silks were reeled from four very different spiders: Araneus diadematus, Nephila edulis, Latrodectus mactans and Euprosthenops sp. They displayed significant differences in behaviour in the native state as well as during and after supercontraction in solvents such as water, urea solution and a set of alcohols. The different polarities of the solvents are thought to affect different regions of the silk's molecular conformation. We hypothesise that the observed mechanical properties of dragline silks are those of a hard elastic polymer; and we explain the supercontraction of the silks as changes of orientation in the molecular chains. q1999 Elsevier Science Ltd. All rights reserved.
Hydrogen bond, Hard elastic biopolymer, Ultrastructure
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【期刊论文】The natural silk spinning process A nucleation-dependent aggregation mechanism?
邵正中, Guiyang Li , Ping Zhou , Zhengzhong Shao , Xun Xie , Xin Chen , Honghai Wang , Lijuan Chunyu and Tongyin Yu
Eur. J. Biochem. 268, 6600-6606(2001),-0001,():
-1年11月30日
The spinning mechanism of natural silk has been an open issue. In this study, both the conformation transition from random coil to b sheet and the b sheet aggregation growth of silk fibroin are identified in the B. mori regenerated silk fibroin aqueous solution by circular dichroism (CD) spectroscopy. A nucleation-dependent aggregation mechanism, similar to that found in prion protein, amyloid b (Ab) protein, and a-synuclein protein with the conformation transition from a soluble protein to a neurotoxic, insoluble b sheet containing aggregate, is a novel suggestion for the silk spinning process. We present evidence that two steps are involved in this mechanism: (a) nucleation, a ratelimiting step involving the conversion of the soluble random coil to insoluble b sheet and subsequently a series of thermodynamically unfavorable association of b sheet unit, i. e. the formation of a nucleus or seed; (b) once the nucleus forms, further growth of the b sheet unit becomes thermodynamically favorable, resulting a rapid extension of b sheet aggregation. The aggregation growth follows a first order kinetic process with respect to the random coil fibroin concentration. The increase of temperature accelerates the b sheet aggregation growth if the b sheet seed is introduced into the random coil fibroin solution. This work enhances our understanding of the natural silk spinning process in vivo.
silk fibroin, spinning mechanism, conformation transition, nucleation-dependent, CD spectroscopy.,
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邵正中, Zhengzhong Shao a, b, Robert J. Young c, Fritz Vollrath a, *
International Journal of Biological Macromolecules 24(1999)295-300,-0001,():
-1年11月30日
We used wel-defined, fluorescence-free Raman spectra of single silk fibres to study silk ultrastructure. Major ampullate (MA) silk was reeled from the Araneus diadematus spider under controlled conditions. With acustom-built stress-strain gauge, we examined the mechanical properties of this silk both before and after supercontraction in a range of solvents. The solvents were found to modify the material properties considerably. We suggest that the solvents with their different polarities affect different regions of the silk's composite microstructure, in particular the conformation of the molecular chains.
Araneus diadematus, Raman spectroscopy, Mechanical testing, Silk ultrastructure
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邵正中, Z. Shao, X. W. Hu, S. Frische, F. Vollrath *
Polymer 40(1999)4709-4711,-0001,():
-1年11月30日
Previous work has shown that dragline silk of Nephila madagascariensis is not homogeneous in cross-section. We report here that the core of Nephila edulis silk also contains extremely fine elongated, electron lucent domains. These domains may contribute to the exceptional tensile strength and toughness of this material by acting as stress concentration parts or (and) fluid-filled canaliculi. q1999 Elsevier Science Ltd. All rights reserved.
Biopolymer, Fibrous protein, Microstructure
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