Keratin Digestion in the Larvæ of the Clothes Moth

Abstract

THE digestion of keratin in the larvæ of the ordinary clothes moth, Tineola biselliella, was investigated by means of the micro-methods developed by Linderstrøm-Lang and Holter. In the secretion of the middle intestine a powerful proteinase was found having a pH optimum about 9.3 (40°, splitting up casein) and, contrary to animal trypsin-kinase, being but little sensitive to addition of thiol compounds (sodium sulphide, sodium thioglycolate). The pH of the secretion of animals fed with wool was about 10 (measured with the glass electrode in a carbon dioxide free chamber) and gave a strong nitro-prusside reaction which was most clearly visible in the half-digested hairs present as contamination in the secretion. The reaction disappeared soon after the secretion had been exposed to the air; only a very small further visible change of the hairs was observable when the secretion (with half-digested hairs) was kept in a moist chamber after removal from the intestine. Animals fed with cotton wool or filter-paper (made inviting to the animal by covering it with a thin film of casein and wool-fat) gave scarcely any nitroprusside reaction, but the reaction reappeared when cystin was added to this food (although this is left quite undigested by the animal).