THE REACTION OF MUSTARD GAS WITH DEOXYRIBONUCLEIC ACID WITH SPECIAL REFERENCE TO THE PYRIMIDINES
Mustard gas was allowed to react with DNA at pH 7.4. After mild acid hydrolysis of the product, the mustard (estimated as sulphur) was found in three fractions: bound to purine, bound to apurinic acid, and a portion bound to neither and whose origin was not apparent. The apurinic acid was degraded to free pyrimidines by perchloric acid hydrolysis. From the hydrolyzate, a cytosine and a thymine derivative were isolated and characterized spectrophotometrically. Protamine titration of the DNA–mustard gas product indicated that primary phosphoryl groups had been esterified. It is difficult to reconcile this conclusion with a previous finding that phosphate esterification did not occur. The latter result was obtained by measuring the release of hydrogen ion during reaction.