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【期刊论文】Silk fibres produced by artificial reeling are superior to those that are spun naturally.
邵正中, Zhengzhong Shao *, Fritz Vollrath †
NATURE|VOL 418|15 AUGUST 2002 ,-0001,():
-1年11月30日
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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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【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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