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A method is described for the hydrolysis of wool which entails successive reduction, carboxymethylation, and digestion with the three enzymes, Pronase, prolidase, and leucine aminopeptidase. The reliability of the method has been checked using two proteins of known composition, viz. ribonuclease A and insulin.Amino acid analyses of enzyme digests of wool and of the low-and highsulphur wool proteins, S-carboxymethylkerateines A and B, are presented. The individual contents of aspartic acid, asparagine, glutamic acid, and glutamine, which cannot be determined by analysis of acid hydrolysates, are presented for the first time.

The carbonyl contents of wool fabrics have been determined by colorimetric analysis after partial acid hydrolysis. Irradiation of dry wool fabrics with simulated sunlight causes an increase in carbonyl content. The rate of production is approximately the same for unbleached, bleached, and fluorescently whitened fabrics, even though these fabrics yellow at markedly different rates. In contrast, irradiation of the same fabrics in water results in few additional carbonyl groups, although extensive yellowing occurs. Thus it seems unlikely that carbonyl groups are directly responsible for yellowing. However, the observation that hydrothermal yellowing of dry-irradiated wool is accompanied by a loss in carbonyl content leads us to suggest that carbonyl groups could be involved indirectly in yellowing. The keto acids present in partial acid hydrolysates of irradiated wool have been identified by reductive amination with sodium 3H-borohydride in ammonia solution, a reaction which converts keto acids to the corresponding 3H-amino acids. The formation of radiolabeled alanine, glycine, proline, serine, threonine, glutamic acid, and tyrosine provides evidence for the photo-oxidation of a number of amino acid residues during irradiation of wool.

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A simple controlled-temperature irradiator is described, which permits fabric samples to be irradiated at air temperatures in the range 35°C to 85°C. Photodegradation of wool fabrics, as assessed by measurement of breaking loads, tear strengths, and yel lowness indexes, increases rapidly as the temperature of irradiation is raised, and occurs 3 to 4 times faster at 75°C than at 35°C. A procedure is described for assessing the level of photoprotection conferred on wool by treatment with a UV absorber of the 2-hydroxybenzophenone type. Consistent lifetime improvement factors are ob tained for most levels of photodegradation, and for exposure either to the artificial light source or to sunlight through window glass.