Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling.

  • William Stirling
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling. Source: Wellcome Collection.

    38/690 (page 8)
    (/) Boil with lime-water = partial coagulation. {g) It gives no sulphur reaction (unlike alkali-albumin). IV. Proteoses or Albumoses are formed as intermediate pro¬ ducts in the peptic and tryptic digestion of proteids. In peptic digestion of albumin, acid-albumin is first formed, and finally peptone. Between the two is the group of proteoses or albumoses—primary and secondary. These proteoses have been subdivided into albumoses, globuloses, caseoses, (fee., according as they are derived from albumin, globulin, or casein. (See “ Digestion.”) Witte’s peptones (i.e., “Commercial peptones”) usually contain a small amount of peptone and much albumose. Make a strong solution by dissolving some in warm water, or io p.c. NaCl. This gives a solution of albumoses. (a) They are soluble in water; not coagulated by heat; and are precipitated by complete saturation with neutral ammonium sulphate. The precipitate with (NH4)2S04 partly disappears on heating, and reappears on cooling. (b) Add nitric acid = a white precipitate which dissolves with heat (yellow fluid) and reappears on cooling. Bun tap water on the tube, the precipitate reappears. This is a characteristic re¬ action, and occurs best in the presence of NaCl. [Salicyl- sulphonic acid gives the same result.] (c) Acetic acid and ferrocyanide of potassium = precipitate which disappears on heating, and reappears on cooling. (d) It is precipitated by acetic acid and saturation with NaCl. The precipitate disappears on heating, and reappears on cooling. (e) It, like peptone, gives a rosy-pink with Piotrowski’s test, i.e., CuS04 + NaHO. (/) They are precipitated but not coagulated by alcohol. (g) To 5 c.c, + 5 c.c. saturated solution of Am2S04 and 4 grms. of the powdered solid. Saturate the mixture in water bath at 35° C. = sticky deposit of albumoses. Filter, and test filtrate for peptones, (h) Add 1 c.c. dil. H2S04 (1 :4) + ZnS04= precipitate. V. Peptones are hydrated proteids, and in the body are pro¬ duced by the action of proteolytic ferments on proteids. They are exceedingly soluble in water, but they are not precipitated by NaCl, acids, or alkalies, nor are they coagulated by heat. They are precipitated by tannic acid, and with difficulty by a large excess of absolute alcohol. Not precipitated by (NH4)2S04 (unlike all other proteids.)