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HSEMOCHROMOGEN. 289
called globin (Preyer, Schulz), and a ferruginous pigment as chief prod-
ucts. According to Lawrow 94.09 per cent protein, 4.47 per cent
hsematin, and 1.44 per cent other bodies are produced in this decom-
position. The globin, which was isolated and studied by Schulz,1
differs from most other proteins by containing a high amount of carbon,
54.97 per cent., with 16.98 per cent of nitrogen. It is insoluble in water,
but very easily soluble in acids or alkalies. It is not dissolved by ammonia
in the presence of ammonium chloride. Nitric acid precipitates it in
the cold, but not when warm. It may be coagulated by heat, but the
coagulum is readily soluble in acids. Because of these reactions it is
considered as a histone by Schulz.
On hydrolytic cleavage globin (from horse-blood) yields, accord-
ing to Abderhalden,2
the ordinary cleavage products of the proteins
and especially leucine, 29 per cent. It is also important to call attention
to the large amount of histidine, 10.96 per cent, while the quantities of
arginine and lysine were only 5.42 and 4.28 per cent respectively.
The pigment split off is different, depending upon the conditions
under which the cleavage takes place. If the decomposition takes place
in the absence of oxygen, a coloring-matter is obtained which is called
by Hoppe-Seyler hcemochromogen, by other investigators (Stokes)
reduced hcematin. In the presence of oxygen, hsemochromogen is quickly
oxidized to hsematin, and there is therefore obtained in this case hcematin
as a colored decomposition product. As hsemochromogen is easily
converted by oxygen into hsematin, so this latter may be reconverted
into hsemochromogen by reducing substances.
Heemochromogen was discovered by Hoppe-Seyler.3
It is, accord-
ing to Hoppe-Seyler, the colored atomic group of hsemoglobin and of
its combinations with gases, and this atomic group is combined with
proteins in the pigment. The characteristic absorption of light depends
on the hsemochromogen, and it is also this atomic group which binds, in
the oxyhsemoglobin, 1 molecule of oxygen and, in the carbon-monoxide
hsemoglobin, 1 molecule of carbon monoxide with 1 atom of iron. Hsemo-
chromogen is produced in an alkaline solution of hsematin by the action
of reducing bodies. By the reduction of hsematin in alcoholic ammoniacal
solution by means of hydrazine v. Zeynek 4 was able to obtain the solid
brownish-red ammonia combination. A crystalline combination between
pyridine and hsemochromogen can be obtained according to Kalmus
1
Lawrow, ibid., 26; Schulz, ibid., 24; Preyer, Die Blutkristalle, Jena, 1871.
2
Zeitschr. f. physiol. Chem., 37; with Baumann, ibid., 51.
3
Ibid., 13.
* Zeitschr. f. physiol., Chem., 25.
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