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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![contained 30.9 p. c. conalbumin, 48.9 p. c. ovalbumin and 20.4 p. c. ovomucoid, so that in this preparation we found [a]D equal to —36° 21'. Of course such determinations cannot be accepted as final, but they are sufficiently accurate to show that conalbumin has a different specific rotation from ovalbumin and is therefore a different substance. This conalbumin appears to be identical with albumin II, described by Panormoff (Chem. Centrabl. 1898, 11, 487), but so far as we can infer from this abstract of his original paper (Jour, russ, phys. Chem. Ges. 30, 302), the substance which he describes under this designation corre- sponds very closely with our fractions C.3, D.i, D.2 and D.3, whose mean rotation and other properties are the same as those given for albumin II. These fractions we have shown to. be mixtures of ovalbumin, conalbumin and ovomucoid. Ovomucoid. After separating all the proteids coagulable by heat, Neumeister (Zeit. f. Biol. N. F. 9, 369, 1890), found in the white of eggs a substance which he called pseudo- peptone. Later Morner (Zeit. f. physiol. Chem. 18, 525, 1893), showed this to be a glycoproteid and named it ovomucoid, under which name it is now generally known. In Table I it is to be noticed that all the fractions following those of the crystallized ovalbumin show an increasing value for [a]D and proportional thereto an increasingly greater content of sulphur. This is chiefly due to ovomucoid associated with these fractions. In connection with the detection of sugar in the albumin molecule, it is important to recognize the difficulty with which ovomucoid can be separated from ovalbumin by fractional precipitation with ammonium sulphate. As we have just shown, fraction F.i contained 12.2 p. c., F.3 23.7 p. c. and F.2.a. 20.4 p. c. of ovomucoid. These fractions were obtained from those immediately following the separation of the crystalline ovalbumin, and F.i was precipitated by simply adding an equal volume of saturated ammonium sulphate solu- tion to the solution of these fractions. We have obtained two preparations of ovomucoid in sufficient quantity for analysis and have found them, when dried at no°](https://iiif.wellcomecollection.org/image/b22469801_0028.jp2/full/800%2C/0/default.jpg)
