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.