The reactivity of the disulphide bonds of wool

1. Fully reduced and S-carboxymethylated wool samples were prepared in which either the readily reducible cystine bonds or those that could only be reduced with difficulty were specifically labelled with iodo[2-(14)C]acetate; these two cystine fractions correspond to the (A+B) and (C+D) cystine fractions respectively, of Middlebrook & Phillips (1942). 2. Radioactively labelled peptides were isolated from partial acid hydrolysates of these wool samples. 3. It appears that the (A+B) cystine residues probably owe their increased reactivity to being in a more polar environment. 4. The implication of these results for the problem of characterizing the disulphide bonds of wool is briefly discussed.     

Unravelling the proteome of wool: towards markers of wool quality traits

With ongoing efforts to make wool more competitive alongside other fibres, notably synthetics, there is a need to obtain a better understanding of the relationship between protein composition and characteristic wool properties to assist sheep breeding programmes. Before this can be achieved, the wool proteome needs to be mapped, by gel and non-gel techniques, and methods developed to reliably quantitate protein expression. Nevertheless, in setting out to achieve this, there are numerous challenges to be faced in the application of proteomics to wool, including the relative lack of wool protein sequence information in the publically accessible databases, the wide variety of proteins in the wool fibre, the high homology within the Type I and Type II keratins, the high degree of homology and polymorphism within individual keratin associated protein families, the dominance of the keratin proteins over others in wool and the peculiar chemistries found in keratins and their associated proteins. This review will discuss the various strategies that have been developed to both identify these proteins in the wool protein map and quantify them with the view to their application to the identification of markers for wool quality traits.     

The dietary-regulated biosynthesis of high-sulphur wool proteins

1. When the diet of sheep is supplemented by the abomasal infusion of sulphur-containing amino acids or casein, a special group of proteins, with a very high content of sulphur (about 8.3%), is incorporated into the high-sulphur proteins of wool. These special proteins cannot be detected in control wool from the same sheep. 2. This is a naturally occurring process, as these special proteins are found in wool from sheep on a high level of nutrition under ordinary conditions of feeding, and in wool of an inherently high sulphur content. 3. This represents a control mechanism in protein synthesis that has not previously been observed, and may be further evidence that the high-sulphur proteins of wool are produced by an unusual synthetic route.     

The role of chitosan in wool finishing

The application of the biopolymer chitosan as an alternative to the conventional contaminating processes in textiles was studied. As chitosan is produced by biomass, it is biodegradable and bioadsorbable. These properties are increasingly important given the current environmental legislation. The main aim of chitosan treatment of oxidised wool fabrics is to improve felting properties and dyeing behaviour.     

Developing the wool proteome

The wool proteome has been largely uncharted due to a lack of database coverage, poor protein extractability and dynamic range issues. Yet, investigating correlations between wool physical properties and protein content, or characterising UV-, heat- or processing-induced protein damage requires the availability of an identifiable and identified proteome.In this study we have achieved unprecedented wool proteome identification through a strategy of comprehensive data acquisition, iterative protein identification/validation and concurrent augmentation of the sequence database. Data acquisition comprised a range of different hyphenated MS techniques including LC–MS/MS, LC–MALDI, 2D-LC–MS/MS and SDS-PAGE LC–MS. Using iterative searching of databases and search result combination using ProteinScape, a systematic expansion of identifiable proteins in the sequence database was achieved. This was followed by extensive validation and rationalisation of the protein identifications. In total, 72 complete and 30 partial ovine-specific protein sequences were added to the database, and 113 wool proteins were identified.Enhanced access to ovine-specific protein identification and characterisation will facilitate all wool fibre protein chemistry and proteomics research.     

The removal of lipid from the surface of wool to promote the subsequent enzymatic process with modified protease for wool shrink resistance

Abstract

When treated with modified protease, wool shows shrink resistance without significant damage to the fiber. It was considered that if wool fiber was pre-treated to make it more hydrophilic, the subsequent treatment with modified protease would be more efficient. After wool was pre-treated with cetyltrimethylammonium bromide (CTAB) under alkaline conditions, the fiber became very hydrophilic due to the removal of surface lipid. After CTAB treatment, it was found that residual CTAB on the fiber significantly decreased enzyme activity. Therefore prior to enzyme treatment, CTAB was washed off the fiber with anionic surfactant under acidic conditions. It was found that the activity of modified protease towards wool improved if wool had been pre-treated with CTAB then washed with anionic surfactant. It was concluded that pre-treatment of wool with CTAB under alkaline conditions followed by washing with anionic surfactant improves the wettability of wool and therefore promotes more efficient treatment with modified protease, achieving improved levels of shrink resistance with no effect on strength of the fiber or coloration properties.