STUDIES OF MUSSEL BYSSAL THREADS AND PROTEIN FILMS FROM ARTIFICIAL SPIDER SILK

Illinois Institute Of Technology, Chicago IL

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The properties of biological materials often exceed those of man-made ones. Two materials with outstanding mechanical properties are the unique anchorage system of the mussel Mytilus galloprovincialis, the mussel byssus, and spider dragline silk. While the mechanical properties of mussel byssal threads resemble those of soft rubber at one end and rigid nylon at the other, spider dragline silk is very tough throughout its length. Our goal is to understand these materials on a molecular level and to access their high potential for biomaterial applications. To this end, we used Fiber X-Ray Diffraction using the micro-diffraction instrument on the BioCAT beamline 18ID and detected significant differences in the orientation and the secondary structure of proteinaceous components along the thread. While the elastic part of the thread consists of less-oriented proteins, the components of the stiff portion are well-oriented along the thread axis. In the stiff thread signals representative for the triple helical structure of collagen were observed. Additionally meridonal reflections indicate a periodic arrangement of the collagen fibrils similar to the D-Period in vertebrate collagen type I. We have also designed and recombinantly produced artificial spider dragline silk proteins. These proteins can be processed into different morphologies, such as films, gels, foams and capsules. We were able to obtain diffraction patterns from films cast from different solutions. We are now working on improved sample preparation methods in order to obtain better resolved diffraction patterns.