On an enzyme from blow-fly larvae [Lucilia sericata] which digests collagen in alkaline solution.

IT is well known that sclero-proteins are not readily digested by the enzymes of vertebrates; both pepsin and trypsin act upon elastin, collagen is very resistant to trypsin but is digested by pepsin, and keratin is not attacked by either enzyme. However, Stankovic, Arnovlzevic and Matavulj [1929] have described a keratinase from the crops of certain birds of prey and Ssadikov [1927] has claimed that a collagenase is present in ox-pancreas and in some commercial samples of pancreatin. According to earlier workers, the pancreatic enzymes are unable to digest collagen [Sahli, 1924]. Lucilia larvae normally develop in meat or carrion, but they are also a serious pest to living sheep, feeding first in the wool and later boring into the tissues. Under suitable conditions the larvae can consume meat entirely, leaving no trace of connective tissue, and, since they cannot ingest solid particles of meat, the digestion of connective tissue must occur outside the body. The larvae secrete a protease which acts in alkaline solution and persists in the excreta [Hobson, 1931]. An investigation, therefore, was made of the action of the excreta on connective tissue proteins. Their action on keratin was also studied, as a keratinase, if present, would explain how the larvae feed in the wool of sheep and penetrate the skin.