Sulphur in protein bodies.

  • Osborne, Thomas B. (Thomas Burr), 1859-1929.
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: Sulphur in protein bodies. 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.

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    paper) that, owing to the natural acidity of the seed, crystallized edestin, as usually prepared, consists of a mixture of compounds of a basic protein molecule with acids, the nature of the acids depending upon the character and proportion of the salts present at the time the edestin was precipitated. Thus, when prepara- tion XXIII, crystallized from ammonium sulphate solution, was suspended in water and neutralized to phenolphthalein by potas- sium hydrate solution, the edestin remained undissolved and was separated by filtration from the water, in which was found a quantity of potassium sulphate corresponding to the amount of acid neutralized. This and another preparation similarly made contained the following amount of total sulphur: XXII. XXIII. ( 1.125 per cent. 1.084 per cent. Sulphur j 1.no ( 1.103 The acidity of these preparations to phenolphthalein was equal to an amount of sulphuric acid corresponding to the excess of sulphur in them above that of the average of I-XXI, all of which latter were made from sodium chloride solutions. These latter preparations, neutralized in the above-described manner, yielded chiefly potassium chloride, but together with this chloride a small proportion of sulphate was always found. The differ- ences in sulphur content of preparations I-XXI are thus explained. This excess of sulphur is therefore not to be regarded as belonging to the protein molecule. The amount of such sulphur is not great, since the total acidity of the pre- parations in no case exceeded 1.2 cc. of a decinormal solution per gram, which corresponds to sulphuric acid containing sul- phur equivalent to 0.19 per cent, of the protein. Such an excess of sulphur is shown by preparations XXII and XXIII in which, as already stated, I found by actual analy- sis that the acidity was due to sulphuric acid. In order to find the true amount of sulphur belonging to the edestin molecule I determined the total sulphur in a very pure and perfectly neutral preparation, made by several times recrys- tallizing edestin chloride, neutralizing its solution to phenol- phthalein and again crystallizing. Two determinations of sul- phur in this preparation gave 0.880 and 0.887.