Silk is a natural product mainly composed by two proteins: fibroin and sericin. Fibroin is the main component of silk fiber and sericin glues the fibroin filaments in the cocoon and in textile is removed by boiling in water (degumming process). Silk can be easily functionalized, and its structure and morphology modulated to match a wide range of working requirements. In recent years, the unique chemical, mechanical, and biological properties of silk have made this natural polymer a highly attractive candidate for the development of innovative biomedicai devices (i.e. scaffolds for tissue engineering). Recently Tamada has reported that sulfated silk proteins show anticoagulant activity like a sulfated natural polysaccharide such as heparin and Gotoh et al. have demonstrated that sulfated silk fìbroins have potential as antiviral material. Here we present an i.r. and Raman study on fibroin and sericin treated with chlorosulfonic acid in pyridine in order to elucidate the mode of linkage of sulfate groups and the amino acids involved as well as the possible conformational changes caused by sulfation. The trend of both IR and Raman spectra of sulfated silk fabrics showed that conformational changes occurred by effect of sulfation and revealed that fibroin covalently bound sulfate groups mainly through the hydroxyl groups of tyrosine and serine leading to the formation of sulfate salts. At higher sulfation rate the formation of organic covalent sulfates may be proved by the appearance of the IR band at 1385 cm-1. This result points out a possible cross-linking of fibroin chains and could explain the formation of an insoluble fraction during the sulfation reaction as reported by Tamada. The involvement of the amine groups of basic residues in the sulfation reaction is not easily detectable. Nevertheless, the increase in intensity of the Raman band at 1164 cm-1 may reasonably account for this. The same trend can be observed in the spectra of sericin. Due to the different amino acid composition and structural organization, sericin seems to react more than fibroin mainly through the hydroxyl groups of serine.

Vibrational spectroscopic study of sulfated silk proteins.

MONTI, PATRIZIA;TADDEI, PAOLA
2006

Abstract

Silk is a natural product mainly composed by two proteins: fibroin and sericin. Fibroin is the main component of silk fiber and sericin glues the fibroin filaments in the cocoon and in textile is removed by boiling in water (degumming process). Silk can be easily functionalized, and its structure and morphology modulated to match a wide range of working requirements. In recent years, the unique chemical, mechanical, and biological properties of silk have made this natural polymer a highly attractive candidate for the development of innovative biomedicai devices (i.e. scaffolds for tissue engineering). Recently Tamada has reported that sulfated silk proteins show anticoagulant activity like a sulfated natural polysaccharide such as heparin and Gotoh et al. have demonstrated that sulfated silk fìbroins have potential as antiviral material. Here we present an i.r. and Raman study on fibroin and sericin treated with chlorosulfonic acid in pyridine in order to elucidate the mode of linkage of sulfate groups and the amino acids involved as well as the possible conformational changes caused by sulfation. The trend of both IR and Raman spectra of sulfated silk fabrics showed that conformational changes occurred by effect of sulfation and revealed that fibroin covalently bound sulfate groups mainly through the hydroxyl groups of tyrosine and serine leading to the formation of sulfate salts. At higher sulfation rate the formation of organic covalent sulfates may be proved by the appearance of the IR band at 1385 cm-1. This result points out a possible cross-linking of fibroin chains and could explain the formation of an insoluble fraction during the sulfation reaction as reported by Tamada. The involvement of the amine groups of basic residues in the sulfation reaction is not easily detectable. Nevertheless, the increase in intensity of the Raman band at 1164 cm-1 may reasonably account for this. The same trend can be observed in the spectra of sericin. Due to the different amino acid composition and structural organization, sericin seems to react more than fibroin mainly through the hydroxyl groups of serine.
XXVIII European Congress on Molecular Spectroscopy
109
109
P. Monti; G. Freddi; C. Arosio; M. Tsukada; T. Arai; P. Taddei
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/38872
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact