The nature of papaïn and its action on vegetable proteid / by Sidney H.C. Martin.

  • Martin, Sidney Harris Cox, 1860-1924.
Date:
[1885]
Catalogue details

Licence: Public Domain Mark

Credit: The nature of papaïn and its action on vegetable proteid / by Sidney H.C. Martin. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    12/32 page 342
    Further the extensive researches of this observer, whicli have been almost universally accepted (even up to 1877 by Sachsse'), discovered the jDrcsence of bodies which he called legumin, conglutin and gluten- casein. Vines has explained the presence of the two first bodies by an action of the alkali (used in extracting them) on the globulins present; the last being also probably due to the same cause. Weyl considers all the caseins described in plants as artificial products. The question cannot be further discussed here : the whole subject has been ably treated by Vines in this journaF. The important fact brought out by the researches of Weyl, Hoppe- Seyler, Zoiler, supplemented by tho.se of Vines, is that there is a constant association of globulins and hemialbumose in the seeds of the plants investigated. This fact will derive still greater significance from the results of the analysis of the proteids in papaw juice, immediately to be detailed. As mentioned above it does not seem to me definitely proved that true peptones are absent from the vegetable kingdom: and to this point I have directed my attention specially. To return to what has previously been said, the hemialbumose described by Vines was, like peptone, soluble in distilled water, and also, like that body, was not precipitated by boiling, and gave a biuret reaction: it differed from peptone in being precipitated by nitric acid and acetic acid and potassic ferrocyanide, and also, according to Vines, in not dialysing. It seemed to me therefore necessary to use a method which would separate the hemialbumose, leaving the peptone, if present, in solution. Several methods were attempted, the readiest of which was found to be Hofmeister’s. It is as follows: to the liquid, which must be neutral, is added half its volume of a saturated solution of sodium acetate, and then dilute ferric chloride till no more blood-red colouration is observed : ferric acetate is formed. The liquid is then neutralised with cau-stic soda, care being taken that it is on the acid rather than on the alkaline side of neutrality, boiled, and afterwards filtered. I'he clear filtrate is free from all proteids except peptones. I have used this test in the digestive filtrates of both pancreatic and papai'n digestions and have found it answer well. In the filtrate there will be no precipitate with nitric acid or with acetic acid and potassic ferrocyanide, showing the absence of hemialbumose; and yet there will ^ Die Farhstoffe, Kohlehydrate, und Proteliufuhxtanzen. Leipzig, 1877. 2 Op. cit.
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