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1.
Biochemistry (Mosc) ; 62(5): 474-9, 1997 May.
Article in English | MEDLINE | ID: mdl-9275287

ABSTRACT

Experiments and hydrolysis of substrates with known spatial structures (such as yeast tRNAPhe, as well as normal and mutant tRNALys from 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 systemic lupus erythematosus (SLE). The antibody preparations contained two types of ribonuclease activities: the first corresponded to the specificity of ribonuclease A and was found during hydrolysis at low salt concentrations, whereas the second was stimulated by Mg2+ and displayed 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 examined. In experiments with unmodified and mutant tRNALys species differing in one base found in the T-loop, we found that hydrolysis with SLE antibodies can detect small local structural changes in RNA under physiological conditions.


Subject(s)
Antibodies, Catalytic/blood , Lupus Erythematosus, Systemic/immunology , RNA, Transfer, Lys/metabolism , Humans , Hydrolysis , Lupus Erythematosus, Systemic/blood , Nucleic Acid Conformation , RNA, Transfer, Lys/chemistry
2.
Biochemistry (Mosc) ; 62(12): 1358-66, 1997 Dec.
Article in English | MEDLINE | ID: mdl-9481869

ABSTRACT

Antibodies (Abs) hydrolyzing proteins, DNA, and RNA are detected in the blood of patients with various autoimmune diseases. In the present work, homogeneous preparations of IgG Abs from the blood of the healthy donors as well as patients with A, B, C, and delta types of viral hepatitis, influenza, pneumonia, tuberculosis, tonsillitis, duodenal ulcer, and some types of cancer were purified. For the first time, the fraction of IgG and its Fab fragments of patients with viral hepatitis were shown to have high DNA- and RNA-hydrolyzing activity. In case of Abs from the healthy donors and patients with other diseases, high activity of Abs was not detected. The data obtained by various methods indicate that the activity of hepatitis Abs is an intrinsic property of the immunoglobulins. The relative rates of hydrolysis of cCMP, poly(U), poly(A), poly(C), and tRNA(Phe) by hepatitis Abs were compared with those of RNase A and other RNases from human blood. Significant differences in activities of Abs and nucleases in hydrolysis of model substrates were demonstrated. Thus, catalytically active Abs can appear in the blood of patients not only with autoimmune disorders, but with viral diseases as well.


Subject(s)
Antibodies, Antinuclear/blood , Antibodies, Catalytic/blood , DNA/metabolism , Hepatitis, Viral, Human/immunology , RNA/metabolism , Antibodies, Antinuclear/immunology , Antibodies, Catalytic/isolation & purification , Base Sequence , Chromatography, Gel , Deoxyribonucleases/metabolism , Electrophoresis, Polyacrylamide Gel , Hepatitis, Viral, Human/blood , Humans , Hydrolysis , Molecular Sequence Data , Nucleic Acid Conformation , RNA/chemistry , Ribonucleases/metabolism
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