The protein constituents of egg white.

  • Thomas Burr Osborne
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: The protein constituents of egg white. 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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    the quantity found in the most thoroughly purified prepara- tions of ovalbumin. Temperature of coagulation. When a solution of conal- bumin is heated sufficiently, a finely divided flocculent coagulum separates which is very difficult from the dense masses that form in a similar solution of ovalbumin. As we could not separate the conalbumin from the other associated proteids except by coagulation, the temperature of coagulation' of this albumin could not be determined under definite conditions. The temperature at which this substance begins to coagulate is influenced by the proportion of salts present. From a solution containing io p. c. of sodium chloride it separates at a lower temperature than from solutions in pure water. From the former solutions it apparently separated completely below 6o°, whereas from the latter it is impossible to separate it from the ovalbumin because the latter begins to coagulate before the separation of the conalbumin is complete. From solutions containing io p. c. of sodium chloride the preparations D.3.1 and K.3.1 separated below 6o°, the solu- tions becoming turbid at about 550. When 2.5 p. c. of K.3, D.3 and F.3 were each dissolved in 10 p. c. brine their solu- tions became turbid at 570, 520 and 58°, and flocks separated at 58°, 550 and 590 respectively. Specific rotation. This we were unable to determine directly, but indirectly the following results were obtained. Of F.i, 1.5 grams were dissolved in 10 p. c. brine, the solution heated to 65°, and the coagulum filtered out and washed. The filtrate was heated to 98° and the coagulum also filtered out and washed. The nitrogen was then determined in each coagulum and in the final filtrate, and the proportion of conalbumin, calculated on the dry preparation, was found to be 25.0 p. c.; of ovalbumin 62.7 p. c.; and of ovomucoid 12.2 p. c. Subtracting the amount of rotation due to the sums of the two latter from the total rotation of F.i, we found the amount of rotation caused by the 25 p. c. of conalbumin, which for 100 p. c. was equal to [«]d —39°- In the same way we found F.3 to contain 36.6 p. c. of conal- bumin, 39.7 p. c. of ovalbumin and 23.7 p. c. of ovomucoid, from which we calculated for the conalbumin [a]D —36°. F.2.a.