Hydroxyapatite chromatography and formamide denaturation of adenovirus DNA

Denatured adenovirus DNA was retained by hydroxyapatite columns under conditions generally used for selective retention of double-stranded DNA, probably due to several partially complementary sequences within single-stranded DNA. It was found that addition of formamide reduced the fraction of sonically treated, denatured adenovirus DNA bound to hydroxyapatite from about 30% to less than 1%. This led to a study of the effect of formamide on the melting temperature (T(m)) of double-stranded DNA in solution or bound to hydroxyapatite. The T(m) of DNA decreases 0.56 C/1% formamide, a value determined in buffered solutions with purified formamide.