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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    poses, however, that in most cases the whole of the loosely- bound sulphur can be counted into lead sulphide under the con- ditions of our experiments. The results obtained with edestin indicate plainly that one-half of its sulphur cannot be thus separated since the highest figures found fell short of one- half of the total sulphur by a quantity decidedly in excess of any probable analytical error. On the other hand, nearly all fell distinctly above one-third. If this is true for edestin it may also be true for some of the other proteins; thus in excelsin the loosely-bound sulphur falls short of two-fifths of the total by nearly the same proportion that it falls short of one-half in edestin. We should, therefore, consider whether or not the proportion of loosely-bound sulphur agrees with a definite num- ber of the sulphur atoms given in Table XXV quite as well as with these simple fractions. In the following table these proteins are given, arranged in the order of their sulphur content; the number of atoms of fixed and loosely-bound sulphur with which the results of the deter- minations agree most closely, assuming the number of atoms of sulphur contained in the molecule to be that shown in Table XXV, the percentage of loosely-bound sulphur found in these proteins; the percentage calculated for the number of atoms of sulphur assumed to be split off; the difference between the amount found and that calculated; and the percentage of the calculated quantity that the amount found is equal to. The amount of loosely-bound sulphur found in those proteins which appear in this table as containing but one atom of such sulphur agrees almost exactly with that calculated. Of those in which a larger number of atoms appear as loosely bound the majority show a deficiency in the amount found compared with that calculated. Before a decision can be reached as to the proportion of loosely-bound sulphur actually contained in the molecules of these different protein bodies, it is necessary to know whether all such sulphur can be obtained as lead sulphide under the conditions of the experiments described in this paper. All investigators who have undertaken to determine the propor- tion of loosely-bound sulphur in the proteins have noted the similarity of the behavior of these substances to that of cystin under similar conditions. Cystin, however, had never been