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The Michael Heidelberger Papers

Letter from Max Delbruck, California Institute of Technology to Michael Heidelberger pdf (185,177 Bytes) transcript of pdf
Letter from Max Delbruck, California Institute of Technology to Michael Heidelberger
In this letter, the prominent biophysicist Max Delbruck asked Heidelberger for reprints of his work on the theory of the precipitin reaction, and himself proposed a mathematical theory for calculating the rate, or velocity, of antigen-antibody reactions.
Item is handwritten.
Number of Image Pages:
4 (185,177 Bytes)
1938-03-16 (March 16, 1938)
Delbruck, Max
California Institute of Technology. Kerckhoff Laboratories of Biology
Heidelberger, Michael
Reproduced with permission of Tobias Delbruck.
Medical Subject Headings (MeSH):
Antigen-Antibody Reactions
Exhibit Category:
Antigens and Antibodies: Heidelberger and The Rise of Quantitative Immunochemistry, 1928-1954
Metadata Record Letter from Michael Heidelberger to Max Delbruck, California Institute of Technology (March 28, 1938) pdf (136,510 Bytes) transcript of pdf
Box Number: 2
Folder Number: 14
Unique Identifier:
Document Type:
Letters (correspondence)
Physical Condition:
Folder: MS C 245 (first finding aid)
March 16, 1938
Dear Dr. Heidelberger,
Dr. L. Pauling and I are planning to run a research-seminar on Protein structure here next term, in which we want to discuss in particular the inferences one can draw from the serological reactions and from their specificity. On going through the literature on the subject we find that we will be rather handicapped by the fact, that most of the immunological journals are not available here in Pasadena. We would appreciate it therefore very much if we could have reprints of your papers on the polysaccharide reactions. When I called on you in October last you were kind enough to let me have reprints of four of your papers from the J. of Exper. Med. (Vol. 65 p. 647 and p. 885, and Vol. 66 p. 229 and p. 251). I wonder whether we could have some more, in particular the theoretical
one from Vol 61 p. 563. I remember that you in October offered this one to me for loan. I looked it up in Cold Spring Harbor but did not study it sufficiently careful, so I would like to see it again. We will of course send it back when we have it sufficiently animilated[?].
I have been speculating a little on the theory of the absolute value of the reaction rate of serological reaction and have arrived at the following formula. Consider the rate of formation of a compound AB from the antigen A and antibody B
A plus B yields AB
In a vessel containing NA particles A and NB particles B. The rate of formation should be dNAB divided by dt equals NA times NB times (DA plus DB) times (aA plus aB) where DA, DB are the diffusion coefficients and a and b the diameter of A and B respectively.
This formula D derived by assuming that every collision between A and B leads to a union. If then D an activation energy, the reaction will be slower, also if the collision must be one between specifically oriented particles. So far as I could test the formula it fits at least the order of magnitude of the observed reaction rates. In your experiments you do not observe this primary reaction but the later stages of formation of the precipitate. One can of course not easily make a theory of the absolute rate of these collisions, but as you have found they seem to be proportional to the concentrations, so they should also be bimolecular reaction. In that case their temperature dependence should be only the result of the temperature dependence of the diffusion coefficients, and this in turn is predominantly determined by the change in viscosity of the solvent, and therefore equal for all
steps in the precipitate reaction. I should be very thankful if your could let me know whether these considerations have been worked out long ago by other people (as I suspect) and where I could find their papers. Ordinary physical chemistry is little concerned with collision numbers in liquids, because the reaction rate on either predominantly determined by activation energy, and any uncertainty in this makes a closer analysis of the collision rates futile, or, if the collision rate determines the reaction rate, the reaction goes immeasurably fast. Therefore the physico-chemical literature does not give a good theory of collision rates.
Yours very sincerely
M. Delbruck
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