Separate Synthesis of Fibrillar and Matrix Proteins in the Formation of Keratin

SummaryVarious amoWlts of DL-methionine or L-cysteine were infused directly into the abomasum of sheep as supplements to a diet of chopped wheaten and lucerne hay, and effects on wool growth and sulphur content of wool were measured.Small amoWlts (0·5-2·0 g/day of L-cysteine or equimolar amounts of :ilL-methionine) increased wool growth by as much as 100%. Similar maximum levels of wool growth were obtained with cysteine or methionine. When larger amoWlts of L-cysteine (6·0-8·0 g/day) were given, the rate of wool growth was reduced to slightly below the maximum response. Administration of equimolar amoWlts of DL-methionine caused a substantial reduction in wool growth; in one experiment the rate of wool growth was depressed to slightly below the pretreatment values.The proportion of the supplementary sulphur accoWlted for in the extra wool grown was inversely related to the amount of amino acid given. With 2·0 g/day of L-cysteine (or equivalent DL-methionine) 23-49% of the supplementary sulphur was recovered in wool.D-Methionine and methionine hydroxy analogue (MHA) were also effective in stimulating wool growth; D-methionine appeared to be less effective than DL-methionine whereas MHA was equivalent to DL-methionine.All sulphur supplements were effective in increasing the sulphur content of wool and similar maximum values were obtained with each supplement. In contrast to effects on wool growth, high levels of L-cysteine or DL-methionine did not depress the sulphur content of wool.

Section: (C) Effects On Sulphur Oontent Of Woolsupporting

confidence: 75%

The Growth and Composition of Wool IV. The Differential Response of Growth and of Sulphur Content of Wool to the Level of Sulphur-Containing Amino Acids given Per Abomasum

Reis¹

1967

“…A similar finding was reported by Kemp and Rogers (1970). The lack of staining in the bulb region, coupled with the progressive increase towards a maximum at the keratogenous zone, provides supporting evidence for the postulated synthesis of high-sulphur proteins within the keratogenous zone (Downes et al 1963;Gillespie 1965).…”

Section: Staining Of Sectionsmentioning

confidence: 82%

Location of a High-sulphur Protein in Developing Wool Follicles Using Peroxidase-Labelled Antibody

Frater¹

1976

Aust. J. Bioi. Sci., 1976,29,453-7 Antiserum to a high-sulphur protein (SCMK -B2) from wool was purified to obtain the immunoglobin G fraction, and this was labelled with horse-radish peroxidase. The labelled antibody was then applied to sections of sheep skin embedded in glycol methacrylate in order to locate the distribution of high-sulphur protein within the lower hair shaft. Regions containing the highest concentration of high-sulphur protein were the cuticle of the hair shaft and the keratogenous zone of the cortex.

“…Valid comparisons are otherwise impossible because of the variations which can occur in the relative amounts of low-and high-sulphur fractions and in the proportions of different components in the latter fraction even in wool grown by the same sheep at different times (Gillespie, Reis, and Schinckel 1964). The second aim was to test further the hypothesis of Downes, Sharry, and Rogers (1963) that soon after injecting [35S]cystine into a sheep the specific activity of the sulphur should be higher in the high-sulphur than in the lowsulphur proteins of the newly synthesized labelled wool. This hypothesis follows from the assumption that keratinization in the wool follicle is a two-stage synthesis in which the proteins of the wool matrix (high-sulphur proteins) are the last to be synthesized (Mercer 1961).…”

Section: Introductionmentioning

confidence: 99%

A Study of the Proteins of the Wool Follicle

Downes¹,

Ferguson²,

Gillespie³

et al. 1966

SummaryA study has been made of the incorporation at different levels in the developing fibre of 35S into the two main protein fractions of wool. The proteins have been studied as the S-carboxymethyl derivatives rather than as the oxidized derivatives previously investigated. The results obtained give further support for a mechanism of synthesis which involves two stages. However, the incorporation of some 35S into the low-sulphur fraction of the keratinized fibre only 24 hr after the injection of [35S]cystine is somewhat surprising and possible explanations for this have been considered. A detailed comparison has been made of the proteins extracted from the unkeratinized portions of wool roots by 8M urea with those which can be extracted from the keratinized residue with urea-thioglycollate. As might be expected the latter proteins were very similar to those isolated from wool itself. The group of urea-soluble, high-sulphur proteins was different in containing considerable amounts of protein lower in both molecular weight and sulphur content than the comparable fraction from the fully keratinized wool. The possibility is discussed that some of these urea-soluble, high-sulphur proteins may be precursors of those in the fully keratinized fibre, conversion taking place by a process of sulphur enrichment.