The protein constituents of egg white.

  • Osborne, Thomas B. (Thomas Burr), 1859-1929.
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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    myosin and fibrinogen. This subject requires further careful study before a definite conclusion can be reached. At present the preponderance of evidence indicates that the carbohydrate is not derived from the protein molecule, but from substances combined with the protein as it is obtained from the tissues or secretions. Conalbumin. Our fractions of the proteids of egg white, obtained after separating the crystallized fractions, all have a higher rotation and sulphur content and a lower temperature of coagulation than ovalbumin, as is shown in Table I. In Table III we showed that these fractions could be separated into two products by heating their solutions to 65°, filtering off the coagulum, and then heating the filtrate to 90°. In the fil- trate from this latter coagulum a substance remained which was not coagulated by boiling. The body coagulating at the lower temperature we designate conalbumin, on account of its close relation in properties and composition to ovalbumin. What this relation may be, we have not determined. Conalbumin and ovalbumin may be different compounds of the same protein, or the former may be a deriva- tive of the latter involving a molecular change. Composition of Coagulated Conalbumin. D.3.1. F.3.1. K.3.I. Average. 1. 11. 1. 11. 1. n. Carbon 52.17 52.20 52-47 52.14 52.25 Hydrogen 6.98 6.70 7 02 7-°7 6.99 Nitrogen 16.04 16.16 16.03 16.15 16.16 16.11 Sulphur 1.67 1.73 I>71 . r-7° Oxygen 23.14 22.64 22.95 10000 100.00 100.00 These figures show very little difference in composition between ovalbumin and conalbumin, the carbon being about 0.5 p. c. lower, the nitrogen about 0.53 p. c. and the sulphur 0.08 p. c. higher. It is possible that the higher sulphur is due to a little ovomu- coid carried down with the coagulum, but this is hardly prob- able, as the ovalbumin coagulated in the filtrates from these preparations contained 1.61 p. c. of sulphur, which is exactly