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OXYHEMOGLOBIN. 281
3-10 per cent for the different oxyhemoglobins. When completely
dried at a low temperature over sulphuric acid the crystals may be
heated to 110-115° C. without decomposition. At higher temperatures,
somewhat above 160° C, they decompose, giving an odor of burned horn,
and leave, after complete combustion, an ash consisting of oxide of
iron. The oxyhemoglobin crystals from difficultly crystallizable blood,
for example from such as ox’s, human, and pig’s blood, are easily
soluble in water. The oxyhemoglobins from easily crystallizable
blood, as from that of the horse, dog, squirrel, and guinea-pig, are soluble
with difficulty in the order above given. The oxyhemoglobin dissolves
more easily in a very dilute solution of alkali carbonate than in pure water,
and this solution may be kept. The presence of a little too much alkali
causes the oxyhemoglobin to decompose quickly. The crystals are
insoluble in absolute alcohol without decolorization. According to
Nencki l
it is converted into an isomeric or polymeric modification,
called by him parahoemoglobin. Oxyhemoglobin is insoluble in ether,
chloroform, benzene, and carbon disulphide.
A solution of oxyhemoglobin in water is precipitated by many metallic
salts, but is not precipitated by sugar of lead or basic lead acetate. On
heating the watery solution it decomposes at about 70° C, and splits
off protein and hematin when sufficiently heated. It is also readily
decomposed by acids, alkalies, and many metallic salts. It gives the
ordinary reactions for proteins with those protein reagents which first
decompose the oxyhemoglobin with the splitting off of protein. Oxy-
hemoglobin, like the other blood-pigments, has a direct oxidizing action
upon tincture of guaiacum. It has, on the other hand, like all blood-
pigments containing iron, the property of an " ozone transmitter " in
that it turns tincture of guaiacum blue in the presence of reagents con-
taining peroxide, such as old turpentine.
A sufficiently dilute solution of oxyhemoglobin or arterial blood
shows a spectrum with two absorption-bands between the Fraun-
hofer lines D and E (spectrum Plate 1). The one band, a, which is nar-
rower but darker and sharper, lies on the line D; the other, broader,
less defined and less dark band, /3, lies at E. The middle of the first
band corresponds to a wave-length X = 579 and the second X = 542. On
dilution the band /3 first disappears. By increased concentration of the
solution the two bands become broader, the space between them smaller
or entirely obliterated, and at the same time the blue and violet part
of the spectrum is darkened. Besides these two bands we can also observe
1
Nencki and Sieber, Ber. d. d. chem. Gesellsch., 18. According to Kriiger (see
Biochem. Centralbl., I, 40, 463) haemoglobin is somewhat changed by alcohol as well
as by chloroform.
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