Formation of the cross-linked base, diguanylethane, in DNA treated with N,N'-bis(2-chloroethyl)-N-nitrosourea

A cross-linked base, diguanylethane, has been isolated and identified as a product of the reaction of N,N'-bis(2-chloroethyl)-N-nitrosourea with DNA. DNA was reacted at 37 degrees with N, N'-bis(2-chloroethyl)-N-nitrosourea in neutral aqueous solutions, isolated by precipitation with ethanol, washed, and heated briefly at 100 degrees to release a purine fraction. This fraction was separated by high-pressure liquid chromatography and found to contain both chloroethylguanine and 1,2-diguanylethane. Formation of the latter product may be related to the cytotoxicity of N,N'-bis(2-chloroethyl)-N-nitrosourea.