Dr. Itano Linus Pauling Jan. 20, 1950
Nature of sickle cell hemoglobin
I think that sickle cell hemoglobin and normal human hemoglobin represent two ways
of coiling the polypeptide chain characteristic of hemoglobin molecule, and that these
two ways are rather stable, being the two stable configurations of the molecule.
This is, of course, the globin molecule.
The evidence available so far indicates the difference in isoelectric point is not
the result of a difference in amino acid composition of the globin. How, it has been
reported, that when hemoglobin is denatured and renatured, it may occur in either
one of two forms, differing in isoelectric point by 1.2 pH units. I think that these
two forms correspond to normal human hemoglobin and sickle ceil anemia hemoglobin.
Would you look up the article by Gralen and tell me what the isoelectric points are
that he reported for the two forms.
I believe that we should repeat Gralen's work, and see if we can prove this point.
Moreover, I think that the two peaks which appear in your electrophoretic patterns
of globin, both normal globin and sickle cell anemia globin, correspond to these two
configurations. If we assume that the isoelectric point of globin is about the same
as that of hemoglobin, 7 or a little less, and draw straight lines on a plot of mobility
against pH to intersect the pH axis, the two lines passing through the observed mobilities
for the slow components and the fast components in acetate buffer, at pH 4.64, we
find that the intercepts differ by 0.23 pH units. The phosphate points do not give
this result, the mobilities of the two components being reported
Dr. Itano -2- 1/20/50
as differing very little. I think that this may be due to a tendency of one of the
globins to find phosphate preferentially, thus changing its charge. The place where
the phosphate is bound is presumably the same place where I believe that heme is bound
because I believe that you found that there was the same difference between sickle
cell anemia hemoglobin and normal hemoglobin in phosphate buffer as in other buffer.
It seems to me that your experiments with globin, showing that the same globin comes
from normal hemoglobin and sickle cell hemoglobin, is pretty good evidence for our
point. I think that to repeat Gralen's experiment with the two hemoglobins would
just about clinch the matter. Would you talk with me about making plans to have this
work carried out?
It seems to me that one thing that we should consider is the possibility of converting
one hemoglobin into the other simply by gentle heating, for a long time, at a temperature
below the denaturation temperature. I suggest that we try the effect of heating both
normal hemoglobin and sickle cell hemoglobin for several days, say, at a temperature
of 58 °C, and then making electrophoretic patterns.
Linus Pauling:W
