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The effect of proline on the network structure of major ampullate silks as inferred from their mechanical and optical properties.
J Exp Biol 2008; 211(Pt 12):1937-47JE

Abstract

The silk that orb-weaving spiders produce for use as dragline and for the frame of the web is spun from the major ampullate (MA) glands, and it is renowned for its exceptional toughness. The fibroins that make up MA silk have previously been organized into two major groupings, spidroin-1 and spidroin-2, based largely on differences in amino acid sequence. The most apparent difference between spidroin-1 and spidroin-2 fibroins is the lack of proline in spidroin-1. The MA silk of Araneus diadematus comprises two spidroin-2 fibroins, and is therefore proline-rich, whereas spidroin-1 is preferentially expressed in Nephila clavipes MA silk, and so this silk is proline deficient. Together, these two silks provide a system for testing the consequences of proline-rich and proline-deficient fibroin networks. This study measures the mechanical and optical properties of dry and hydrated Araneus and Nephila MA silks. Since proline acts to disrupt secondary structure, it is hypothesized that the fibroin network of Araneus MA silk will contain less secondary structure than the network of Nephila MA silk. Mechanical and optical studies clearly support this hypothesis. Although the dry properties of these two silks are indistinguishable, there are large differences between the hydrated silks. Nephila silk does not swell upon hydration to the same degree as Araneus silk. In addition, upon hydration, Nephila MA silk retains more of its initial dry stiffness, and retains more molecular order, as indicated by birefringence measurements.

Authors+Show Affiliations

Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, British Columbia, Canada, V6K 1Z4.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18515724

Citation

Savage, Ken N., and John M. Gosline. "The Effect of Proline On the Network Structure of Major Ampullate Silks as Inferred From Their Mechanical and Optical Properties." The Journal of Experimental Biology, vol. 211, no. Pt 12, 2008, pp. 1937-47.
Savage KN, Gosline JM. The effect of proline on the network structure of major ampullate silks as inferred from their mechanical and optical properties. J Exp Biol. 2008;211(Pt 12):1937-47.
Savage, K. N., & Gosline, J. M. (2008). The effect of proline on the network structure of major ampullate silks as inferred from their mechanical and optical properties. The Journal of Experimental Biology, 211(Pt 12), pp. 1937-47. doi:10.1242/jeb.014217.
Savage KN, Gosline JM. The Effect of Proline On the Network Structure of Major Ampullate Silks as Inferred From Their Mechanical and Optical Properties. J Exp Biol. 2008;211(Pt 12):1937-47. PubMed PMID: 18515724.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effect of proline on the network structure of major ampullate silks as inferred from their mechanical and optical properties. AU - Savage,Ken N, AU - Gosline,John M, PY - 2008/6/3/pubmed PY - 2008/10/10/medline PY - 2008/6/3/entrez SP - 1937 EP - 47 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 211 IS - Pt 12 N2 - The silk that orb-weaving spiders produce for use as dragline and for the frame of the web is spun from the major ampullate (MA) glands, and it is renowned for its exceptional toughness. The fibroins that make up MA silk have previously been organized into two major groupings, spidroin-1 and spidroin-2, based largely on differences in amino acid sequence. The most apparent difference between spidroin-1 and spidroin-2 fibroins is the lack of proline in spidroin-1. The MA silk of Araneus diadematus comprises two spidroin-2 fibroins, and is therefore proline-rich, whereas spidroin-1 is preferentially expressed in Nephila clavipes MA silk, and so this silk is proline deficient. Together, these two silks provide a system for testing the consequences of proline-rich and proline-deficient fibroin networks. This study measures the mechanical and optical properties of dry and hydrated Araneus and Nephila MA silks. Since proline acts to disrupt secondary structure, it is hypothesized that the fibroin network of Araneus MA silk will contain less secondary structure than the network of Nephila MA silk. Mechanical and optical studies clearly support this hypothesis. Although the dry properties of these two silks are indistinguishable, there are large differences between the hydrated silks. Nephila silk does not swell upon hydration to the same degree as Araneus silk. In addition, upon hydration, Nephila MA silk retains more of its initial dry stiffness, and retains more molecular order, as indicated by birefringence measurements. SN - 0022-0949 UR - https://www.unboundmedicine.com/medline/citation/18515724/The_effect_of_proline_on_the_network_structure_of_major_ampullate_silks_as_inferred_from_their_mechanical_and_optical_properties_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=18515724 DB - PRIME DP - Unbound Medicine ER -