Capillary Electrophoresis of Urinary Normal and Modified Nucleosides of Cancer Patients

RNA molecules contain a number of modified nucleosides, in addition to the normal ribonucleosides adenosine, guanosine, cytidine, and uridine. More than 90 different modified nucleosides with great structural diversity have been described in RNA (1 ), most of them in tRNA, but some also in rRNA, mRNA and small nuclear RNA (snRNA). The modifications are formed posttranscriptionally within the polynucleotide molecule by numerous different modification enzymes, in particular by methyltransferases and ligases. Some of the modified nucleosides occur only in one species of RNA, whereas others occur in several species (1 ,2 ). The function of the modified nucleosides of RNA is not quite clear. It has been suggested that tRNA modification plays a structural and regulatory role (3 ).