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SERALBUMIN*. 261
and carbohydrate acids of unknown kinds. It has not boon shown
whether these small amounts of carbohydrate are derived from the globulin
or from other contaminating bodies. According to Zanetti and also
Bywaters, the blood-serum contains a glucoproteid, seromucmd, and
the investigations of Eichholz * seem to show that the globulins are
contaminated by a glucoproteid. According to Langstein the sugar
is not only mixed with the globulin, but it exists in a combined form,
probably in loose combination.
Serglobulin (the euglobulin) may be easily separated as a fine floc-
eulent precipitate from blood-serum by neutralizing or making faintly
acid with acetic acid and then diluting with 10-20 vols of water. For
further purification this precipitate is dissolved in dilute common salt
solution, or in water with the aid of the smallest possible amount of
alkali, and then reprecipitated by diluting with water or by the addition
of a little acetic acid. All the serglobulin may also be separated from
the serum by means of magnesium or ammonium sulphate; in these
cases it is difficult to completely remove the salt by dialysis. As long
as we are not agreed as to the number of globulins in the serum, it is
not necessary to give a method of separating the various globulins in this
mixture. Thus far the fractional precipitation with (NH^SCU has
chiefly been used. The serglobulin from blood-serum is always contam-
inated with lecithin and thrombin. A serglobulin free from thrombin
may be prepared from ferment-free transudates, as sometimes from
hydrocele fluids, and this shows that serglobulin and thrombin are dif-
ferent bodies. For the detection and the quantitative estimation of
serglobulin we may use the precipitation by magnesium sulphate added
to saturation (Hammarsten), or by an equal volume of a saturated
neutral ammonium-sulphate solution (Hofmeister and Kauder and
Pohl 2
). In the quantitative estimation the precipitate is collected on a
weighed filter, washed with the salt solution employed, dried with the
filter at about 115° C, then washed with boiling-hot water, so as to
completely remove the salt, extracted with alcohol and ether, dried,
weighed, and incinerated to determine the ash. This method, according
to the investigations of Wiener,3
can only be used when the serum is
sufficiently diluted with water.
Seralbumins are found in large quantities in blood-serum, blood-
plasma, lymph, transudates, and exudates. Probably they also occur
in other animal fluids and tissues. The proteins which pass into the
urine under pathological conditions consist largely of seralbumin.
The seralbumin, like the serglobulin, seems also to be a mixture of
at least two protein bodies. The preparation of crystalline seralbumin
1
Zanetti, Chem. Centralbl., 189S, I, p. 624; Bywaters, Journ. of Physiol., 35, and
Biochem. Zeitschr., 15; Eichholz, Journ. of Physiol., 23.
2
Hammarsten, 1. c; Hofmeister, Kauder and Pohl, Arch. f. exp. Path. u. Pharm., 20.
3
Zeitschr. f. physiol. Chem., 74.
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