ACYLATION OF CYSTOSINE BY ETHYL N-HYDROXYCARBAMATE AND ITS ACYL DERIVATIVES AND BINDING OF THESE AGENTS TO NUCLEIC ACIDS AND PROTEINS

Ethyl N-hydroxycarbamate and several of its acyl derivatives specifically acylated the primary amino-group of cytosines; no reaction occurred at other sites or with the other nucleic acid bases. Compared with cytosine, the N(4)-acylcytosines showed (a) a bathochromic shift in u.v. absorption and (b) an increase in the polarity of the carbon-nitrogen bond resulting in greater ease of hydrolysis into uracils. [1-3H]Ethyl N-hydroxycarbamate and ethyl [acetyl-3H]N-acetoxycarbamate reacted with nucleic acids and proteins. Incubation of ethyl N-acetoxy-N-acetylcarbamate with DNA, followed by enzymatic hydrolysis of the nucleic acid, produced 2′-deoxyuridine and 2′(5′)-deoxyuridylic acid. Ethyl carbamate and acetylcarbamate, and several other acyl derivatives of ammonia, hydrazine, and hydroxylamine did not react with cytosine.