Interviewee: Erwin Chargaff. Erwin Chargaff talks about his discovery - a major step for building the DNA model. (DNAi Location: Code > Finding the structure > Players > Erwin Chargaff > Chargaff's ratio)

We found, as I say, that there were constant quantities of each of the nucleotides in a given DNA, that is if we isolated from three different sperm preparations, human DNA, hydrolyzed these separately and determined quantitatively the content in the various nucleotides or, or bases, they would be constant for the species but different for different species. So that for instance we could find the 27 percent adenine, that means also 27 percent thymine, and in the other one we could find 52 percent adenine and 52 percent thymine. So that a compound, these quantitative results were constant for the species but different from each other. So this was something which was completely unusual, unknown in biology, I would say, that these thousands of protein analyses and I don't think one can find a single one in which certain amino acids and identical characteristic amounts that this is repeatable amounts so that this was definitely unique for me at least.

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