Keratin

KERATIN belongs to the group of albumoids, or albuminoids, and is the main constituent of the supporting and covering tissues of the animal organism, entering into the composition of horny tissue, epidermis, hair, wool, feathers, the shell of a tortoise, etc.; it possesses great resistance to various chemical agents that dissolve proteins. In the form of neurokeratin it enters into the composition of brain tissue and nerves. Elementary analyses of K. of different tissues have shown an unequal content of C, H, O, S, and N in it. The greater part of the sulfur enters into the composition of cystine and is easily detached under the action of alkalis; part of the sulfur is detached even upon heating with water. K. is amorphous, insoluble in water, alcohol, and ether. Upon heating with water up to 150-200° K. dissolves. It is easily soluble in alkalis, especially upon heating. It does not dissolve in artificial gastric juice and in solutions of trypsin. It gives the xanthoproteic and Millon reactions, though not always typically. To obtain K., finely crushed horny tissue is first treated with boiling water, then successively with an acid solution, hydrochloric solution of pepsin, alkaline solution of trypsin, and finally with water, alcohol, and ether. K. does not dissolve in acidic gastric juice; therefore K. is used to coat pills containing medicines whose action it is desirable to have in the intestine and not in the stomach. In therapy K. was applied without special success for the treatment of tabes and disseminated sclerosis. In recent times, treatment by iontophoresis with a 7% solution of keratin in aqueous ammonia and in wine alcohol is again applied against hair loss. K. is applied internally in tablets of 0.5 to 10 tablets a day; subcutaneously, a 2:10 solution, 1 cm³ per injection.