RNA-HYDROLYZING ANTIBODIES FROM PERIPHERAL-BLOOD OF PATIENTS WITH LUPUS-ERYTHEMATOSUS

Experiments with hydrolysis of substrates with known spatial structure s (such as yeast tRNA(Phe), as well as normal and mutant tRNA(Lys) fro m human mitochondria produced by transcription of the appropriate DNA species, that is, RNA genes) were performed to study the ribonuclease activity of antibodies isolated from blood sera of patients with syste mic lupus erythematosus (SLE). The antibody preparations contained two types of ribonuclease activities: the first corresponded to the speci ficity of ribonuclease A and was found during hydrolysis at low salt c oncentrations, whereas the second was stimulated by Mg2+ and displayed a unique specificity toward double-stranded regions of the substrate. The possible use of the antibody preparations as tools for structural studies of conformational differences between RNA molecules was exami ned. In experiments with unmodified and mutant tRNA(Lys) species diffe ring in one base found in the T-loop, we found that hydrolysis with SL E antibodies can detect small local structural changes in RNA under ph ysiological conditions.