The Unique Ribbon Morphology of the Major Ampullate Silk of Spiders from the Genus Loxosceles (Recluse Spiders)
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- 作者：Jonathan A. Coddington ; Henri D. Chanzy ; Catheryn L. Jackson ; Gail Raty ; and KennCorwin H. Gardner
- 刊名：Biomacromolecules
- 出版年：2002
- 出版时间：January 2002
- 年：2002
- 卷：3
- 期：1
- 页码：5 - 8
- 全文大小：229K
- 年卷期：v.3,no.1(January 2002)
- ISSN：1526-4602
文摘
The morphology of silk produced by recluse spiders (Loxosceles arizonica) was investigated by scanningelectron microscopy, atomic force microscopy, and transmission electron microscopy. This silk consistedentirely of very long, thin ribbons of width 2-4 
m and thicknesses of no more than 40 nm. The correspondence in shape and dimension between the silk ribbons and the elongated aperture of the major ampullatespigot indicated that these ribbons were major ampullate silk. Selected area electron diffraction patternsfrom single ribbons were indexed with an orthorhombic unit cell (a = 9.43(2) Å, b = 8.96(3) Å, c =6.96(1) Å). This unit cell is in good agreement with that previously reported for synthetic poly(L-alanylglycine).Thus it is likely that the crystalline regions of the major ampullate silk of L. arizonica consist of an alternatingglycine-L-alanine motif that has adopted a 
-sheet structure. The amino acid composition achieved withthe silk of L. arizonica as well as that of L. laeta confirmed that the major amino acid constituents of thissilk were glycine and L-alanine in nearly equal amounts. As it was noticed that the dry ribbons were highlyelectrostatic, it is suggested that the electrostatic interaction plays an important role in prey capture forLoxoseles.
m and thicknesses of no more than 40 nm. The correspondence in shape and dimension between the silk ribbons and the elongated aperture of the major ampullatespigot indicated that these ribbons were major ampullate silk. Selected area electron diffraction patternsfrom single ribbons were indexed with an orthorhombic unit cell (a = 9.43(2) Å, b = 8.96(3) Å, c =6.96(1) Å). This unit cell is in good agreement with that previously reported for synthetic poly(L-alanylglycine).Thus it is likely that the crystalline regions of the major ampullate silk of L. arizonica consist of an alternatingglycine-L-alanine motif that has adopted a -sheet structure. The amino acid composition achieved withthe silk of L. arizonica as well as that of L. laeta confirmed that the major amino acid constituents of thissilk were glycine and L-alanine in nearly equal amounts. As it was noticed that the dry ribbons were highlyelectrostatic, it is suggested that the electrostatic interaction plays an important role in prey capture forLoxoseles.