The effect on the molecular concentration and electrical conductivity of muscle extracts of removal of the proteids / by G.N. Stewart.

  • Stewart, G. N. (George Neil), 1860-1930.
Date:
[1899?]
Catalogue details

Licence: Public Domain Mark

Credit: The effect on the molecular concentration and electrical conductivity of muscle extracts of removal of the proteids / by G.N. Stewart. Source: Wellcome Collection.

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    show a different behaviour towards them from the albumins, which are soluble in water. The number of experiments hitherto made have not been sufficient to disclose any constant difference between the various proteids of muscle extracts. The conductivity of the muscle extract is less than that of the magnesium sulphate solution used in making it. This is probably not due to the dilution of the solution by water passing into it from the muscle, since the molecular concentration of the muscle extract is greater than that of the solution both before and after the removal of the proteids. And indeed the magnesium sulphate solution being hypoisotonic to serum, and therefore presumably to the contents of the muscle fibres (which, according to Loeb are isotonic with a 0*7 p.c. solution of NaCl), water might rather be expected to pass into the muscle from the solution. The fact that A is uniformly greater for the muscle extracts than for the magnesium sulphate solutions used, while the conductivity of the extracts is less than that of the solutions, is accounted for by the passage from the muscle into the extract of non-conducting substances, not only proteids but glycogen, glucose, etc. As regards the effect of removal of the proteids on the freezing point the results are somewhat variable, and that to an extent greater than can be accounted for by errors in the freezing point determinations. Thus in Exp. 3 the removal of T132 grm. paramyosinogen from 100 c.c. of extract diminished A by '015°, while subsequent removal of T246 grm. myosinogen increased it by the same amount, bringing it back exactly to its original value. In Exp. 4 A remained constant within the limits of error of the method, while in Exp. 5 the removal of the paramyosinogen and myosinogen increased A by '004°, and the removal of all the proteids increased it by ’028°. These irregularities I am not at present in a position to explain, but hope that further experiments may discover their cause. I suspect that they may be due, in part at any rate, to changes taking place in the proteids during the heating, for example hydrolysis. In Exp. 2 the effect of dialysis on the conductivity of a 5 p.c. magnesium sulphate extract of muscle is shown. After several days it was reduced to one-seventh of its original value, but later on began to increase again. This increase is doubtless associated with the development of acid which constantly accompanies the precipitation of the muscle proteids, and with putrefactive changes.