Letter from Linus Pauling to Michael Heidelberger

In this letter Linus Pauling, the world's preeminent physical chemist at the time, asked Heidelberger to comment on a hypothesis regarding the chemical structure of antibodies and the location of the sites at which they bind to antigens Pauling had developed. Pauling's article was published as "A Theory of the Structure and Process of Formation of Antibodies" in the Journal of the American Chemical Society 62 (1940), pp. 2643-2657.