Chemistry and Structure of the Protein Fibres

Protein fibres are grouped into animal fibres (wool and other animal hairs, known also as a-keratin fibres) and insect fibres (silk, a fibroin fibre). Both 

Total hydrolysis of the peptide bonds in proteins yields the 20 common natural a-amino acids given in Table 9.6.1 (cystine, thiocysteine and cysteine are considered to be faces of the same amino acid). More than 100 amino-acids bind to each other to form the protein chains, schematically shown subsequently. 

Amino acids with hydroxyl groups in the side chain Serine Threonine Tyrosine -CH2-OH -CH(CH2)-0H -CH2-C6H4-OH 

Sulphur-containing amino acids Cysteine Thiocysteine Cystine Methionine -CH2-SH -CH2-S-SH -CH2-S-S-CH2- -(CH2)2-S-CH3 

Amino acids without reactive groups in the side chain Glycine Alanine Valine Proline -H -CH3 -CH(CH3)2 —CHj. 

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