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OVOGLOBULIN. OVALBUMIN. G33
The protein substances of the white of egg behave like glycoproteins,
as they all yield glucosamine. For the globulin and albumin it has not
been proved, nor is it probable? that the glucosamine belongs to the pro-
tein molecule (sec page 84). According to the solution and precipita-
tion properties they arc similar to the globulins, albumins or proteoses.
The representatives of the first two groups, are ovoglobulin and ovalbumin.
The proteose-like body is ovomucoid.
Ovoglobulin separates in part on diluting the egg-white with water.
It is precipitated upon saturation with magnesium sulphate, or upon
one-half saturation with ammonium sulphate, and coagulates at about
75° C. By repeated solution in water and precipitation with ammonium
sulphate a part of the globulin becomes insoluble (Langstein). This
also occurs on precipitation by diluting with water or by dialysis, and
it is quite possible that the globulin is a mixture. That portion which
readily becomes insoluble seems to be identical with Eichholz’s gly-
coprotein or Osborne and Campbell’s ovomucin. Langstein obtained
11 per cent of glucosamine from the soluble ovoglobulin. The total
quantity of globulins, according to Dillner, is about 6.7 per cent of
the total protein substances, and this corresponds with the recent deter-
minations of Osborne and Campbell. In regard to the probable occur-
rence of several globulins in the white of the egg there are the determina-
tions of Corin and Berard as well as of Langstein,1
but they have
not led to any positive conclusions.
Ovalbumin. The so-called albumin of the egg-white is undoubtedly
a mixture of at least two albumin-like proteins. Opinions differ con-
siderably in regard to the number of these proteins (Bondzynski and
Zoja, Gautier, Bechamp, Corin and Berard, Panormoff, and others).
Since Hofmeister has been able to prepare ovalbumin in a crystalline
form, and since Hopkins and Pinkus 2
have shown that not more than
one-half of the ovalbumin can be obtained in such a form, Osborne and
Campbell have isolated two different ovalbumins or principal fractions;
the crystallizable they call ovalbumin and the non-crystallizable con-
albumin. The two fractions have only a slight variation in elementary
composition; the conalbumin coagulates between 50-60° C, nearer to
60° C, and the ovalbumin at 64° C or at a higher temperature. There
are no conclusive investigations as to whether the non-crystallizal le
1
Langstein, Hofmeister’s Beitrage, 1; Eichholz, Journ. of Physiol., 23; Osborne
and Campbell, Connecticut Agric. Exp. Station., 23d Ann. Report, New Haven, 1900;
Dillner, Maly’s Jahresber., 15; Corin and Berard, ibid., 18.
2
Hofmeister, Zeitschr. f. physiol. Chem., 14, 16, and 24, Gabriel, ibid., 15; Bond-
zynski and Zoja, ibid., 19; Gautier, Bull. Soc. chim., 14; Bechamp, ibid., 21; Corin
and Berard, 1. c.; Hopkins and Pinkus, Ber. d. d. ehem. Gesellsch., 31, and Journ. of
Physiol., 23; Osborne and Campbell, 1. c.; Panormoff, Maly’s Jahresber., 27 and 28.
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