Linus Pauling: So, in 1936 I gave a Ground Rounds talk at the Rockefeller Institute for Medical
Research, in New York, about hemoglobin. And after my talk, Karl Landsteiner asked
if I would come to his laboratory and talk with him. He was doing very interesting
work. He had discovered the blood groups back in 1900, A-B both.
And he was then making studies of the reactions of antibodies and the antigens --
homologous antigens or heterologous antigens. And in fact it was the sort of work
that would appeal to a chemist because he would take a chemical off the shelf -- something
with known structure, a simple substance -- and couple it to a protein, usually by
diacetation of the amino group, and inject this azoprotein into a rabbit and get antibodies
which were characteristic of this simple chemical. He would get a solution of protein
molecules that would combine specifically with the chemical that he had took off the
shelf -- something that no rabbit had ever seen before.
This was surely interesting to me, another example of biological specificity. These
immune reactions are about as specific as you can get. You can detect the difference
between, say, hen egg ovalbumin and duck egg ovalbumin when, up until recently, there
were no other ways of showing that these two closely-related proteins were in fact
different from one another.