Small molecules in silks

Thesis

Whereas most silk research is focused on silk proteins, the focus of this thesis is on small molecules present in silk and why they are so important for anyone working in this field with silk.

Silks are known to perform a range of different functions in nature, whereas for people, silk can be used in a wide variety of applications. A major disadvantage of using silk in these applications however, is its large variation in properties. In this thesis, the importance of small molecules will be discussed in light of this variation.

I present for the first time that calcium oxalate monohydrate is present in the cocoons of Wild Silkmoths resulting in the inability of reeling these cocoons. Furthermore, a method was developed for removing this mineral coating resulting in that these cocoons could be reeled for the very first time, what has vast commercial implications. Additionally, I found that the cocoon spinning between B. mori and G. postica was significantly different resulting in a mineral-free cocoon for B. mori.

Further, an unknown polyphenol in dragline and egg sac silk was identified responsible for the yellow coloration of these silks. An enzymatic method for the synthesis of this molecule was found in vitro and was believed to happen similarly in vivo. Whereas the function of this molecule is still unknown, the extended hydrogen bonding capabilities suggest it will bind to the silk peptide.

Finally we highlight the importance of small molecules in silk and point at the significance of the food of silkmoths and spiders as the origin of these small molecules, which has never been controlled for in any research or application.

Authors: Gheysens, T

• Publication date: 2011
• DOI: 10.5287/ora-qrrbggnv6
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: mineralization; tanning; silk; small molecules; pigment; demineralizing
• Subjects: Behaviour (zoology); Chemical biology; Biomimetic synthesis; Molecular biophysics (biochemistry); Materials Sciences; Spectroscopy and molecular structure; Advanced materials; Biology