242
AUSTEN RIGGS
preciable, the molecular weight could not be calculated by a simple
determination of the S and D values.
Component F has a lower oxygen affinity (P5,, = 30 mm) at “physiological pH” than any other teleost fish reported (most others are apparently under 20 mm) and a very large Bohr effect (Fig. 8), in contrast
to component S which has a much higher affinity and no Bohr effect.
This remarkable difference accounts completely for the observation that
the oxygen equilibria are biphasic at pH 7.0-7.2, and that at pH 6.8 the
oxygenation level at 100 mm po2 is only 45% which is the proportion that
is component S. They found no change in the oxygen affinity for either
component between 0.2 and 0.8% in protein concentration. The shapes
of the oxygen equilibria for both components are sigmoid with an n
value of ~ 2 . 4 .
Perhaps the most interesting observation is that the two
components are affected very differently by phosphate. The oxygen
affinity of component F, but not S, decreases when the phosphate is increased from 0.03 it1 to 1.0 M. This curious finding suggests that intracellular phosphates may be particularly important in controlling the
2 .o
I .o
Fig, 8. Comparison of the Bohr effects of components F and S of the hemoglobin of the chum salmon, obtained at 15°C in 0.1 M phosphate ( Hashimoto et al.,
1960). The value of ( A log P,,)/(A pH) for component F reaches a value of 1.25,
as high as known for any hemoglobin.
AUSTEN RIGGS
preciable, the molecular weight could not be calculated by a simple
determination of the S and D values.
Component F has a lower oxygen affinity (P5,, = 30 mm) at “physiological pH” than any other teleost fish reported (most others are apparently under 20 mm) and a very large Bohr effect (Fig. 8), in contrast
to component S which has a much higher affinity and no Bohr effect.
This remarkable difference accounts completely for the observation that
the oxygen equilibria are biphasic at pH 7.0-7.2, and that at pH 6.8 the
oxygenation level at 100 mm po2 is only 45% which is the proportion that
is component S. They found no change in the oxygen affinity for either
component between 0.2 and 0.8% in protein concentration. The shapes
of the oxygen equilibria for both components are sigmoid with an n
value of ~ 2 . 4 .
Perhaps the most interesting observation is that the two
components are affected very differently by phosphate. The oxygen
affinity of component F, but not S, decreases when the phosphate is increased from 0.03 it1 to 1.0 M. This curious finding suggests that intracellular phosphates may be particularly important in controlling the
2 .o
I .o
Fig, 8. Comparison of the Bohr effects of components F and S of the hemoglobin of the chum salmon, obtained at 15°C in 0.1 M phosphate ( Hashimoto et al.,
1960). The value of ( A log P,,)/(A pH) for component F reaches a value of 1.25,
as high as known for any hemoglobin.