Practical physiological chemistry; a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . of Filtrate from Ox Spleen.—The filtrate from the copper sul-phide should be evaporated to dryness on the water-bath. Extract with coldwater. Test a part of this aqueous solution with picric acid. A lack of precipi-tate indicates the absence of adenine. To another portion add anmionia (alack of precipitate indicates the absence of guanine), and then a Uttle ammo-niacal silver nitrate solution (lack of appreciable precipitate indicates absence ofpuri
Practical physiological chemistry; a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . of Filtrate from Ox Spleen.—The filtrate from the copper sul-phide should be evaporated to dryness on the water-bath. Extract with coldwater. Test a part of this aqueous solution with picric acid. A lack of precipi-tate indicates the absence of adenine. To another portion add anmionia (alack of precipitate indicates the absence of guanine), and then a Uttle ammo-niacal silver nitrate solution (lack of appreciable precipitate indicates absence ofpurines of any kind in more than traces). Dissolve half of the residue, whichshould consist mainly of uric acid and xanthine, in as few drops of concentratedsulphuric acid as possible and dilute with 4 volumes of water. Stir until theuric acid begins to separate and then let stand for about three hours. The uricacid is completely precipitated. Apply the murexide test. To the remainderof the xanthine-uric acid residue add a Uttle 4 per cent potassiimi hydroxide solu-tion. Warm and add an equal volume of 30 per cent nitric acid. Allow to Fig. 40.—Hypoxanthine Chloride.^(Reproduced from crystals furnished by Professor Walter Jones.) Xanthine nitrate separates out in a granular form, showing characteristic crystals under the microscope. Apply the nitric acid test. What does the presence of uric acid and xanthine and the absence of guanineand adenine indicate as to the purine enzymes of ox spleen? E. Demonstration of Nucleotidase (Phosphonuclease).—In this experimentuse the 50 portion of enzyme solution retained from Experiment A a 2 per cent solution of yeast nucleic acid aiding the solution by the slowaddition of KOH solution until the reaction, as indicated by a few drops of Utmusadded, is neutral. Prepare a series of three large test-tubes as follows: In No. iplace 10 of enzyme solution and 5 of nucleic acid. In No. 2 place 10 enz
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiochem, bookyear1916
