The dietary-regulated biosynthesis of high-sulphur wool proteins

Abstract

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 Keratin Proteins of Wool, Horn and Hoof from Sheep

“…The wool components are not present in equal proportions and this is especially true of component 5. It has been found that the Dorset Horn wool high-sulphur and low-sulphur proteins have electrophoretic patterns indistinguishable from those previously obtained for Merino wool (O'Donnell and Thompson 1964;Gillespie and Reis 1966;Fraser et al 1972;Crewther et al 1976). It was also found, in agreement with earlier observations (Gillespie 1968(Gillespie , 1972, that the constituent protein fractions are present in different relative proportions in these keratins-for example, the highsulphur protein content of wool, horn, and hoof is 29, 11 and 11 % respectively; the high-tyrosine protein content of wool, horn and hoofis 9, 13 and 10 % respectively.…”

“…The reasonably high sulphur content of the wool (3·75 %) indicates the presence of ultra-high-sulphur proteins (Gillespie and Reis 1966), and the presence of these proteins was confirmed by an electrophoretic run at pH 11 (Fig. 1, indicated by arrow).…”

“…Moving boundary electrophoresis (Gillespie and Reis 1966) was carried out in two 0·1 ionic strength buffers: sodium acetate-acetic acid, pH 4·5, and ,a-alanine-sodium hydroxide, pH 11·0. Protein concentrations were about 1·3 %.…”

“…The latter proteins were dissolved in 0·05 M borate, dialysed against deionized water and stored frozen. The full details of the procedures are given by Reis (1966) andGillespie (1972).…”

Studies On Reduced Wool Ix. The N-Terminal Sequence of A Fragment Produced by Cleavage of Component 8 With Cyanogen Bromide

“…The outstanding role of sulphur in keratin chemistry and biosynthesis (cf. Gillespie and Reis 1966) Arginine 22·0 29·3 23·0 26·2 11·16 2·1 17·6 24·7 Aspartic acid 7·51 40·1 7·65 34·8 8·26 6·5 1·6 3·05 Threonine 3·61 19·3 3·47 15·8 4·09 3·2 7·2 4·69 Serine 5·47 29·2 4·57 20·8 11·66 9·1 9·7 9·98 Glutamic acid 12·22 65·2 14·28 65·0 4·90 3·8 8·1 2·30 Proline 2·53 13·5 1·41 6·41 6·73 5·3 8·0 5·96 Glycine 3·10 16·6 2·08 9·48 7 ·15 5·6 5·8 12·8 Alanine 4·30 22·9 4·01 18·3 2·89 2·3 2·8 2·98 Val...…”