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OXYHEMOGLOBIN. 279
a.
t fi. )
y. and 6-oxyhsemoglobin, all having the same absorption-spectrum, and 1
pram combining with respectively 0.4, 0.8, 1.7, and 2.7 cc. oxygen at the tem-
perature of the room and with an oxygen pressure of 150 mm. mercury. The
7-oxyha>moglobin is the ordinary one obtained by the customary method of
preparation. Bohk designates as a-oxyhaunoglobin the crystallin powder
obtained by drying Y-oxyhsemoglobin in the air. On dissolving a-oxyhaemo-
globin in water it is converted into j3-oxylurmoglobin without decomposition,
and the quantity of iron is increased. On keeping a solution of 7-oxyhaimoglobin
in a sealed tube it is transformed into 5-oxhyaemoglobin, although the exact
conditions under which this change takes place are not known. According to
Hufner ’ these are nothing but mixtures of genuine and partly decomposed
haemoglobins.
The ability of haemoglobin to take up oxygen seems to be a function
of the iron it contains, and when this is calculated as about 0.33-0.40
per cent, then 1 atom of iron in the haemoglobin corresponds to about
2 atoms or 1 molecule of oxygen. By increasing the partial pressure as
well as by increasing the quantities of oxygen, the haemoglobin in solu-
tion takes up more oxygen, until it is completely saturated, when 1 mole-
cule of haemoglobin is combined with 1 molecule of oxygen. With reduced
oxygen pressure a dissociation must naturally take place and oxygen
is given off, and a re-formation of haemoglobin takes place, and this makes
it possible to expel completely the oxygen from an oxyhaemoglobin solu-
tion or blood by means of vacuum, or by passing an indifferent gas
through the solution. The equilibrium between oxyhaemoglobin, haemo-
globin, and oxygen depends, therefore, according to Hufner, upon
a mass action, corresponding to the formula Hb-f-02<=^Hb02. Bohr 2
has arrived at the conclusion that not only a double dissociation takes
place, in which a dissociation of the oxygen-iron combination in the
oxyhaemoglobin occurs, but also a dissociation of the haemoglobin
into a ferruginous as well as into a non-ferruginous part. Correspond-
ingly he has suggested another formula and hence the dissociation curves
for oxyhaemoglobin given by Hufner and Bohr are different.
Important investigations have recently been carried out on this
question by Barcroft and his co-workers Camis and Roberts from
which it follows that a generally valid dissociation curve cannot be given,
as the curve direction is dependent upon the nature and concentration
of the salts present in the solution. A haemoglobin solution with the salts
of the blood-corpuscles of the dog gives a dissociation curve of dog-blood
while with the salts from human blood-corpuscles it gives a curve like
human blood. In the presence of salts the dissociation follows Bohr’s
formula, and on the contrary while a salt-free haemoglobin solution follows
the oxygen combination according to the mass-action law of Hufner.
1
Arch. f. (Anat. u.) physiol., 1894.
2
Bohr, Centralbl. f. physiol., 17, pp. 682 and 688.
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