Hydrolysis of the proteins of maize, Zea Mays / by Thomas B. Osborne and S.H. Clapp.

  • Osborne, Thomas B. (Thomas Burr), 1859-1929.
Date:
[1908]
Catalogue details

Licence: In copyright

Credit: Hydrolysis of the proteins of maize, Zea Mays / by Thomas B. Osborne and S.H. Clapp. 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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    total yield of free glutaminic acid obtained on this hydrolysis 83.71 gin., or 16.32 per cent of the protein, while by the direct method 18.28 per cent was obtained. Glutaminic Acid. Osborne and Gilberts found 16.87 Per cent of glutaminic acid in zein, but as the amount of protein available for that determination was only 32 gm. we have repeated the determination with the fol- lowing results: 100 gm. equal to 91.6 gm. moisture, ash, and fat free zein from the “ gluten-meal ” was heated on a water bath for two and a half hours with 200 c.c. of hydrochloric acid sp. gr. 1.19, and then boiled in an oil bath for twelve hours. After concentrat- ing the hydrolysis solution to about two thirds its original volume it was saturated with hydrochloric acid gas and allowed to stand for some days on ice. There were thus obtained 20.9 gm. of glu- taminic acid hydrochloride equal to 16.74 gm. glutaminic acid, or 18.28 per cent. Tyrosine. Kutscher 8 9 has stated that zein yields 10.06 per cent of tyrosine. We have made every effort to isolate all the tyrosine possible from our solutions, but have obtained barely one third as much as Kutscher. Although we are convinced that tyrosine still remained in our solutions, we have obtained no evidence that the amount that defied separation was more than relatively small in proportion to that which did separate. As several unusual observations were made in the course of our efforts to separate the last traces of tyrosine, we will give a brief description of them. Three hundred grams of the zein from the “ gluten meal ” were hydrolyzed with 900 gm. of sulphuric acid and 1800 gm. of water by heating on the water bath for ten hours and then boiling in an oil bath for ten hours longer. After removing the sulphuric acid with an equivalent quantity of baryta and thoroughly washing the barium sulphate, the filtrate and washings were concentrated to about 2500 c.c. and cooled. The substance that separated, when 8 Osborne and Gilbert: This journal, 1906, xv, p. 333. 8 Kutscher, Zeitschrift fur physiologische Chemie, 1903, xxxviii, p. in.