Chargaff Rules

In the short but eventful history of molecular biology, Erwin Chargaff must rank as one of the most interesting and one of the most tragic. I also feel that he is long overdue for – if not a reassessment – than at least a re-appreciation. Chargaff is best known for what are now called the “Chargaff Rules,” the observation that in DNA: 1) A + G = C + T (i.e. the sum of the purines equals the sum of the pyrimidines) 2) the molar ratio of adenine to thymine = 1 3) the molar ratio of guanine