Radiation-induced crosslinks between carboxylic acids and compounds of biological interest

Various carboxylic acids having short carbon chains (10(-4) or 5 X 10(-4) M) mixed with serum albumin or DNA (1 mg/ml) were irradiated in phosphate buffer solution (10(-3) M, pH 7.0) with 60Co gamma rays. Maleic acid and nicotinic acid showed high binding activity resulting from having an unsaturated double bond and an aromatic ring, respectively. Sodium salts of C18 fatty acids (0.5 mg/ml) such as stearate, oleate, linoleate, and linolenate were also irradiated in the presence of amino acids or nucleobases (10(-4) or 5 X 10(-4) M) in the same buffer solution. The binding yield increased with the increase in the number of double bonds indicating participation of double bonds in the binding.