Studies on the binding of 6-mercaptopurine by ribonucleic acids in the presence of metals

Abstract

6-MP-S 35 combines with yeast RNA when they are mixed at room temperature. Extraction with hot TCA does not remove copper or 6-MP-S 35 from the nucleic acid. Treatment with H 2S removes about 50% of the nucleic acid copper and 50% of the combined 6-MP-S 35. Addition of copper ions to nucleic acid solutions increases the amount of 6-MP binding by the nucleic acid, and hot TCA extraction removes the extra 6-MP bound by added copper ions but does not remove 6-MP bound in the absence of added copper. When the SH group of 6-MP is blocked with a methyl group, combination with RNA does not occur. Adenine and hypoxanthine do not combine with RNA. The effect of copper ions on the spectra of 6-MP and some of its analogs is reported.