Ab8tractWool samples can vary in their content of tyrosine by as much as 60%. It has been shown that this is due to variation in their content of a heterogeneous group of proteins which are very rich in tyrosine and glycine (about 1 residue in 5 and 1 residue in 3 respectively). Certain Lincoln wools and some felting lustre mutant Merino wools appear to contain very little of these proteins whereas fine Merino wools may contain as much as 12% by weight of them. As this is too much protein to be accommodated in the cuticular membranes, the currently held site of origin of hightyrosine proteins, it is concluded that at least some of these proteins must be accommodated in an unknown region of the cortex.The variable tyrosine content of wools may be related to observed differences in their rate of photochemical degradation and mechanicochemical properties.

No abstract

A study has been made of the high-sulphur protein components of wools from goats and a variety of sheep using electrophoresis in starch gels at pH 2·4 and chromatography on DEAE-cellulose at pH 4·5 as methods for characterization. The high-sulphur proteins prepared from ovine wools, from domestic (10 breeds and strains), feral (Soay and Shetland), or wild (Bighorn, O. canadensis; Mouflon, O. mU8'imon) sheep are very heterogeneous. Of the two methods gel electrophoresis gives the better resolution with a characteristic pattern in which upwards of 20 components can be seen and 12 are sufficiently well separated to be readily identifiable. This pattern is unaffected by the diet or by the age of the sheep (up to 5 yr) and would seem to be characteristic for ovine wools. One or other of two of these bands may be missing from the wool of some individuals, particularly of wild sheep.Significant departures from this pattern were observed with high-sulphur proteins of non-ovine wools (Barbary sheep, Amnotraguslervia; Blue sheep, Pseudois nayaur) and the hair of the domestic goat (Oapra sp.), although they were equally heterogeneous. This electrophoretic technique may be of use in clarifying the somewhat uncertain phylogenetic relationships within the sheep-like and goat-like animals. High-sulphur proteins from the wool of six sheep having the felting lustre mutation gave patterns which differed from the standard ovine pattern in characteristic individual ways.

S-Carboxymethyl derivatives of the high-sulphur components of reduced Merino wool have been subdivided by chromatography into 17 fractions, the amino acid compositions of which are reported. Tryptic, chymotryptic, and thermolysin digests of each fraction have been studied by high-voltage paper electrophoresis at pH 3�5 and 6�5. The results suggest that the high-sulphur proteins consist of families of proteins probably containing common structural features. Evidence is presented that the heterogeneity of high-sulphur proteins is not artefactual.

Diflubenzuron 90% pre-concentrate and its 25% water-dispersible powder were analyzed by a high performance liquid chromatographic method. Six samples were extracted with 1,4-dioxane, linuron was added as internal standard, and diflubenzuron was separated on a 25 cm × 4.6 mm column packed with Zorbax BP-C8 with acetonitrile-water-l,4-dioxane (450 + 450 + 100) at 1.3 mL/min and monitored at 254 nm. Results were obtained from 17 laboratories. Within-laboratory repeatability was 0.6% for both the pre-concentrate and the water-dispersible powder samples and the reproducibility was 1.2%. The method has been adopted as a full CIPAC method and was adopted official first action by AOAC.