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.

    9/20 (page 485)
    washed with cold water and thoroughly dried at ioo°, weighed 22.8 gm., I. The filtrate and washings were concentrated to about 1200 c.c. and similarly yielded 19^88 gm. of II. On further con- centration 12 gm. of III were obtained and 16.27 gm. of IV. The filtrate from IV, when concentrated to a syrup, gave 27.75 g™. of V, from which the thick mother liquor could not be very thor- oughly sucked out. The total yield of substances that were thus separated in a solid state capable of removal by filtration was about one third of the hydrolyzed zein. Small parts of the five fractions were then treated with glacial acetic acid in which IV and V were completely soluble at the room temperature, II and III were mostly soluble, while I contained much that did not dissolve. The whole of Fractions I, II, and III were therefore treated with an abundant quantity of glacial acetic acid, the residue filtered out, washed with absolute alcohol, and when dried at ioo° weighed 8.27 gm. (crude tyro- sine A). The acetic acid solution filtered from A was freed from acetic acid as completely as possible by repeatedly evaporating under diminished pressure with water and with alcohol and then subjected to extensive fractional crystallization. The less soluble fractions, which closely resembled nearly pure leucine, when recrystallized gave no Millon’s reaction, whereas, although the most soluble frac- tions gave strong Millon’s reactions, no tyrosine could be obtained from them in characteristic crystals. All the fractions which gave Millon’s reaction were set aside for further examination. Fraction IV was dissolved in water, the solution treated with bone-black and subjected to fractional crystallization. There was obtained 9.35 gm. of the original 16.27 gm. which did not give Millon’s reaction; but the second fraction, which was very soluble in water, gave a Millon’s reaction, while the filtrate from this, on concentration to a syrup and adding alcohol, gave a gummy deposit which would not harden under alcohol and gave a strong Millon’s reaction. A similar fractional recrystallization of V yielded no fractions which did not give a strong Millon’s reaction. • The thick syrup that had been separated from V was then treated with alcohol, and on long standing a product separated that could be sucked out but contained so muph mother liquor that it could not be weighed. This was redissolved, its solution treated with bone- black and concentrated, and 8.8 gm. of substance obtained which gave a moderately strong Millon’s reaction.