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SERUM PROTEINS. 2G3
The crystalline and amorphous seralbumin in aqueous solution give
the ordinary albumin reactions. The coagulation temperature of a
1-per cent solution, poor in salts is about 50° C, but rises with the quan-
tity of salt. The coagulation of the mixture of albumins from serum
generally takes place at 70-85° C, but is essentially dependent upon
the reaction and the amount of salt present. Up to the present time no
seralbumin solution has been prepared free from mineral bodies. A
solution as free from salts as possible does not coagulate either on boil-
ing or on the addition of alcohol. On the addition of a little common
salt it coagulates in both cases. 1
Seralbumin differs from the albumin of the white of the hen’s egg in
the following particulars: It is more levogyrate; the precipitate formed
by hydrochloric acid easily dissolves in an excess of the acid; it is rendered
less insoluble by alcohol.
In preparing the seralbumin mixture, first remove the globulins,
according to Johansson, by saturating with magnesium sulphate at
about 30° C. and filtering at the same temperature. The cooled filtrate
is separated from the crystallized salt and is treated with acetic acid so
that it containes about 1 per cent. The precipitate formed is filtered
off, pressed, dissolved in water with the addition of alkali to neutral
reaction, and the solution freed from salt by dialysis. The mixture of
albumins may be obtained in a solid form from the dialyzed solution,
either by evaporating the solution at a gentle temperature or by pre-
cipitating with alcohol, which must be quickly removed. Starke 2
has suggested another method, which is also to be recommended. The
crystalline seralbumin may be prepared from serum freed from globulin
by half saturating with ammonium sulphate, by the addition of more
salt until a cloudiness appears, and then proceeding according to the
suggestion of Gurber and Michel. On acidifying with acetic acid
or sulphuric acid the crystallization may be considerably accelerated.3
The quantity of seralbumin is best calculated as the difference between
the total proteins and the globulins. A method for the quantitative
estimation of globulins and albumins in blood serum by refractometric
means has been suggested by Robertson.4
Summary of the elementary composition of the above-mentioned and described
proteins (from horse-blood):
c h n s
Fibrinogen 52 . 93 6 . 90 16 . 66 1 . 25 22 . 26 (Hammarsten)
Fibrin 52.68 6.83 16.91 1.10 22.48
Fibrin-globulin 52.70 6.98 16.06
Serglobulin 52.71 7.01 15.85 1.11 23.32
Seralbumin 53 . CS 7.10 15 . 93 1 . 90 21 .86 (Michel)
’In regard to the relationship of neutral salts to heat coagulation,, see J. Starke,
Sitzungsber. d. Gesellsch. f. Mori>h. u. Physiol, in Munehen, 1897.
2
Johansson, Zeitschr. f. fhvsiol. Chem., 9; K. Staike, Maly’s Jahresber., 11.
3
See Hopkins and Pinkus, Journ. of Physiol., 23; Krieger, I’eber die Darstellung.
krystallinscher tierischer Eiweissstoffe, Inaug.-Dissert. Strassburg, 1899.
* Journ. of biol. Chem., 11.
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