Abstract
The reaction of yeast ribonucleic acid (RNA) with malonaldehyde. a product of lipid oxidation, at pH 4 and 37 C produced modified RNA with absorption at 325 nm and fluorescence. The fluorescence intensity was extremely low as compared with that of bovine serum albumin modified similarly. Torula yeast transfer RNA (tRNA), calf thymus deoxyribonucleic acid (DNA). polycytidylic acid (polyC) and polyadenylic acid (polyA) underwent similar modification. The modification took place at cytosine, adenine and probably guanine residues. The absorption maximum at 325 nm may he due to the modified cytosine and adenine residues, which form 1 : 3 adducts with a methylene cyclopropane ring and a six-membered ring (Nair et al., J. Am. Chem. Soc., 106, 3370 (1984)). These modifications did not produce any significant fluorescence. The present data are inconsistent with those of Reiss et al. (Biochcm. Blophys. Res. Commun., 48. 921 (1972)), who reported that the modification of nucleic acids with malonaldehyde produced fluorescent cross-links due to conjugated Schiff bases.
