DETECTION OF METHYLGLYOXAL AS A DEGRADATION PRODUCT OF DNA AND NUCLEIC-ACID COMPONENTS TREATED WITH STRONG ACID

The 1,g-diaminobenzene derivatization assay for methylglyoxal in biolo gical systems involves the use of perchloric acid, both as a deprotein izing agent and to prevent the spontaneous formation of methylglyoxal from glycolytic pathway intermediates. However, while using a modifica tion of the standard literature assay to measure methylglyoxal in Chin ese hamster ovary cells, we found that oxidation of nucleic acids and related compounds by perchloric or trichloroacetic acid results in the formation of methylglyoxal. Compounds containing 8-deoxyribose gave h igher levels of methylglyoxal. than those containing ribose; purine nu cleotides and deoxynucleotides gave more methylglyoxal than did the py rimidines. Nucleic acids were the most susceptible to degradation, wit h la-fold more methylglyoxal being formed from DNA than RNA. Oxidation of nucleic acids increased with higher temperatures and with decreasi ng nucleic acid fragment size. Another product of nucleic acid oxidati on was 2,3-butanedione, the 1,2-diaminobenzene derivative of which is sometimes used as an internal standard during methylglyoxal measuremen t. Unless accounted for during the assay procedure, the generation of methylglyoxal and 2,3-butanedione due to the oxidation of nucleic acid s may lead to substantial errors in the determination of methylglyoxal concentrations in biological systems. (C) 1996 Academic Press, Inc.