Transactions of the Connecticut Academy of Arts and Sciences Volume 8 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 Excerpt: ...hydrochloric acid was sufficient to entirely prevent any digestive action whatever. Doubtless, even smaller amounts of acid would have the same influence on the more perfectly isolated ferment. As already stated, saturation of pineapple juice, either neutralized or of natural acidity, with ammonium sulphate precipitates all or nearly all of the proteids present in the fluid, the precipitate showing by its proteolytic action that it contains the ferment as well. An aqueous solution of such a precipitate, dialyzed to free it from ammonium sulphate, has a marked digestive action, but when mixed with hydrochloric acid its proteolytic power, like that of the alcohol precipitate, is immediately checked. Experiment VIII.--Aqueous, dialyzed solution of the above described ammonium sulphate precipitate. The amount of dry albumin equivalent to the 10 grams of moist coagulum used in the digestions was 1-5120 grams. The mixtures were warmed at 40 C. for 5 hours. Undissolved Percent. Ferment solution. Reaction. albumin. digested. A 100" + 100"H2O neutral 1-1791 grams 22-1 B 100 +100 0-2 HCl 0-l'HCl 1-4897 1-0 As previously stated, pineapple juice, and the isolated ferment as as well, manifests its proteolytic action in an alkaline-reacting fluid, as well as in the presence of an acid or neutral reaction. When, however, the solution becomes strongly alkaline proteolytic action is quickly retarded, the ferment in this respect differing very decidedly from the related ferments papain and trypsin. Thus, the addition of small quantities of sodium carbonate to neutralized pineapple juice, a few hundredths of one per cent., produces no noticeable effect, but as the quantity is increased the retarding action of the alkali becomes more pronounced, until at last it...