6. PFIOPEFWIES OF FISH HEMOGLOBINS
243
oxygen affinity. Although phosphate concentrations as high as 1 M were
used, siibstantial effects were observed at much lower concentrations.
Below 0.1 M in phosphate the value of ( A log P , , ) / ( A log [Phos]) is
about 0.32 which indicates that about 1.3 phosphate ions are released
for each tctramer oxygenated. At much higher concentrations, more is
bound. The oxygen equilibrium of component F is much more sensitive
to temperature than is that of tomponent S.
Two hemoglobins with properties as different as those of F and S
might reflect an adaptation to changes in physiology or to environment.
However, Hashimoto and Matsuura (196Ob) found no correlation of
the proportions with place of capture, temperature of water, body length,
or sex. Although they found no clear evidence for an ontogenetic
change in proportions, such changes have been found in other species
of salmon (Vanstone et aZ., 1964; Wilkins, 1968; see Section 11, A, 2).
Yoshioka et nl. (1968) havc isolated the two major hemoglobins from
the eel, Anguillu juponica, and have determined the oxygen equilibrium.
Most of their results are quite similar to the earlier measurements of
Yamaguchi et al. ( 1962) on the eel and on the loach (Yamaguchi et aZ.,
1963). Indeed it is remarkable that in salmon, eel, and loach two hemoglobins are present with such similar properties. Components I and I1
of the eel hemoglobin are each composed of two kinds of polypeptide
chain and possess no chain in common. Just as with the salmon hemoglobin, one component (11) has a large Bohr effect, while the other
( I ) has none. They report that mixtures of I and I1 give oxygen equilibria
which give no evidence of interaction between the components. They
have also compared the oxygen equilibrium of erythrocytes suspended
in an isotonic buffer of pH 7.0 both with a hemolyzate and with a 3:7
mixture of components I and 11; all three sets of data were essentially
indistinguishable. This result is very hard to understand because the
pH inside the erythrocytes cannot be the same as that outside. The
isoelectric points are 8.08 and 5.96 for components I and 11, respectively
(Yoshioka et al., 1968). Component I has no Bohr effect and so can be
ignored for the present purposes, but component I1 has a large Bohr
effect. A difference in pH, between the inside and outside of the red
cell, would not cause any change in the oxygen equilibrium of component
I, but component I1 would be negatively charged and so the pH would
be substantially lower inside the red cell than outside. Their data show
that the minimum oxygen affinity occurs close to pH 7; any shift in pH
from 7 would therefore cause an increase in affinity, although this would
not be detected if the log P,,, vs. pH plot has a sufficiently broad maximum.
Steen and Turitzin (1968) found that the degree of oxygenation of
erythrocytes and of hemolyzed blood from the eel, AnguiZZa d g a r i s ,
243
oxygen affinity. Although phosphate concentrations as high as 1 M were
used, siibstantial effects were observed at much lower concentrations.
Below 0.1 M in phosphate the value of ( A log P , , ) / ( A log [Phos]) is
about 0.32 which indicates that about 1.3 phosphate ions are released
for each tctramer oxygenated. At much higher concentrations, more is
bound. The oxygen equilibrium of component F is much more sensitive
to temperature than is that of tomponent S.
Two hemoglobins with properties as different as those of F and S
might reflect an adaptation to changes in physiology or to environment.
However, Hashimoto and Matsuura (196Ob) found no correlation of
the proportions with place of capture, temperature of water, body length,
or sex. Although they found no clear evidence for an ontogenetic
change in proportions, such changes have been found in other species
of salmon (Vanstone et aZ., 1964; Wilkins, 1968; see Section 11, A, 2).
Yoshioka et nl. (1968) havc isolated the two major hemoglobins from
the eel, Anguillu juponica, and have determined the oxygen equilibrium.
Most of their results are quite similar to the earlier measurements of
Yamaguchi et al. ( 1962) on the eel and on the loach (Yamaguchi et aZ.,
1963). Indeed it is remarkable that in salmon, eel, and loach two hemoglobins are present with such similar properties. Components I and I1
of the eel hemoglobin are each composed of two kinds of polypeptide
chain and possess no chain in common. Just as with the salmon hemoglobin, one component (11) has a large Bohr effect, while the other
( I ) has none. They report that mixtures of I and I1 give oxygen equilibria
which give no evidence of interaction between the components. They
have also compared the oxygen equilibrium of erythrocytes suspended
in an isotonic buffer of pH 7.0 both with a hemolyzate and with a 3:7
mixture of components I and 11; all three sets of data were essentially
indistinguishable. This result is very hard to understand because the
pH inside the erythrocytes cannot be the same as that outside. The
isoelectric points are 8.08 and 5.96 for components I and 11, respectively
(Yoshioka et al., 1968). Component I has no Bohr effect and so can be
ignored for the present purposes, but component I1 has a large Bohr
effect. A difference in pH, between the inside and outside of the red
cell, would not cause any change in the oxygen equilibrium of component
I, but component I1 would be negatively charged and so the pH would
be substantially lower inside the red cell than outside. Their data show
that the minimum oxygen affinity occurs close to pH 7; any shift in pH
from 7 would therefore cause an increase in affinity, although this would
not be detected if the log P,,, vs. pH plot has a sufficiently broad maximum.
Steen and Turitzin (1968) found that the degree of oxygenation of
erythrocytes and of hemolyzed blood from the eel, AnguiZZa d g a r i s ,