Tyrosinase-catalyzed modification of Bombyx mori silk fibroin

Grafting of chitosan under heterogeneous reaction conditions

Giuliano Freddi (Corresponding Author), Anna Anghileri, Sandra Sampaio, Johanna Buchert, Patrizia Monti, Paola Taddei

Research output: Contribution to journalArticleScientificpeer-review

97 Citations (Scopus)

Abstract

The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10–11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear evidence of the formation of silk-chitosan bioconjugates under heterogeneous reaction conditions. Chitosan grafting caused a β-sheet → random coil conformational transition of silk fibroin and significant changes in the thermal behaviour. Chitosan grafting did not occur, or occurred at an undetectable level on silk fibres. The results reported in this study show the potential of the enzymatically initiated protein–polysaccharide grafting for the production of a new range of bio-based, environmentally friendly polymers.
Original languageEnglish
Pages (from-to)281 - 294
JournalJournal of Biotechnology
Volume125
Issue number2
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Fingerprint

Fibroins
Bombyx
Silk
Monophenol Monooxygenase
Chitosan
Tyrosine
Powders
Oxidation
Gels
Raman Spectrum Analysis
Raman spectroscopy
Fibers
Hot Temperature
Quinones
Agaricales
Substrates
Vibration
Polymers

Keywords

  • Bombyx mori silk fibroin
  • Chitosan
  • Tyrosinase
  • FT-IR
  • FT-Raman
  • DSC

Cite this

Freddi, Giuliano ; Anghileri, Anna ; Sampaio, Sandra ; Buchert, Johanna ; Monti, Patrizia ; Taddei, Paola. / Tyrosinase-catalyzed modification of Bombyx mori silk fibroin : Grafting of chitosan under heterogeneous reaction conditions. In: Journal of Biotechnology. 2006 ; Vol. 125, No. 2. pp. 281 - 294.
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Tyrosinase-catalyzed modification of Bombyx mori silk fibroin : Grafting of chitosan under heterogeneous reaction conditions. / Freddi, Giuliano (Corresponding Author); Anghileri, Anna; Sampaio, Sandra; Buchert, Johanna; Monti, Patrizia; Taddei, Paola.

In: Journal of Biotechnology, Vol. 125, No. 2, 2006, p. 281 - 294.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Tyrosinase-catalyzed modification of Bombyx mori silk fibroin

T2 - Grafting of chitosan under heterogeneous reaction conditions

AU - Freddi, Giuliano

AU - Anghileri, Anna

AU - Sampaio, Sandra

AU - Buchert, Johanna

AU - Monti, Patrizia

AU - Taddei, Paola

PY - 2006

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N2 - The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10–11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear evidence of the formation of silk-chitosan bioconjugates under heterogeneous reaction conditions. Chitosan grafting caused a β-sheet → random coil conformational transition of silk fibroin and significant changes in the thermal behaviour. Chitosan grafting did not occur, or occurred at an undetectable level on silk fibres. The results reported in this study show the potential of the enzymatically initiated protein–polysaccharide grafting for the production of a new range of bio-based, environmentally friendly polymers.

AB - The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10–11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear evidence of the formation of silk-chitosan bioconjugates under heterogeneous reaction conditions. Chitosan grafting caused a β-sheet → random coil conformational transition of silk fibroin and significant changes in the thermal behaviour. Chitosan grafting did not occur, or occurred at an undetectable level on silk fibres. The results reported in this study show the potential of the enzymatically initiated protein–polysaccharide grafting for the production of a new range of bio-based, environmentally friendly polymers.

KW - Bombyx mori silk fibroin

KW - Chitosan

KW - Tyrosinase

KW - FT-IR

KW - FT-Raman

KW - DSC

U2 - 10.1016/j.jbiotec.2006.03.003

DO - 10.1016/j.jbiotec.2006.03.003

M3 - Article

VL - 125

SP - 281

EP - 294

JO - Journal of Biotechnology

JF - Journal of Biotechnology

SN - 0168-1656

IS - 2

ER -