Detection of adenosine diphosphate-ribosyl transferase activity in the filarial worm, Onchocerca volvulus.

The existence of the nuclear enzyme ADP-ribosyl transferase in the filarial worm Onchocerca volvulus was demonstrated. The enzyme activity was observed in the nuclear preparation from the parasitic organism. Poly(ADP-ribose) was identified as the reaction product by the isolation of phosphoribosyl-AMP and 5'AMP as the major products of snake-venom phosphodiesterase digestion. The temperature and pH optima for the enzyme were 25 degrees C and 8.5, respectively. The apparent Km value exhibited by the substrate NAD+, is 750 microM and the activity of the enzyme is inhibited by four chemical classes of inhibitors, nicotinamides, methylxanthines, thymidine and aromatic amides.

Distribution of hepatic ribosomes between different functional states in well-fed and protein-energy-deficient rats.

Electron microscopy of hepatic cells from protein-deficient young rats revealed extensive breakdown of the rough endoplasmic reticulum into fragments and vesicles whose membranes appeared fully studded with ribosomes. Additionally, there was biochemical evidence of marked disaggregation of polysomes (n greater than 2), and this was more prominent in the membrane-bound than in free polysomes. Protein malnutrition increased the proportion of membrane-bound ribosomes which were salt-releasable and therefore temporarily non-functional. It has been concluded that disaggregation of membrane-bound polysomes induced by malnutrition does not necessarily imply detachment of the monomeric ribosomes from the endoplasmic membrane into the pool of free ribosomes, which probably has a separate polyribosomal cycle.

ADP-ribosyltransferase in Plasmodium (malaria parasites).

The nuclei of Plasmodium yoelii nigeriensis contain an enzyme, ADP-ribosyltransferase, that will incorporate the ADP-ribose moiety of NAD+ into acid-insoluble product. The time, pH and temperature optima of this incorporation are 30 min, 8.5 and 25 degrees C respectively. Maximum stimulation of the enzyme activity is obtained with 1.0 mM-dithiothreitol or 2.0 mM-2-mercaptoethanol. Ca2+ and Mg2+ ions at optimum concentrations of 5 mM and 10 mM respectively stimulated the activity of the enzyme by 21% and 91%. The enzyme activity is, however, inhibited by 24% in the presence of 10 mM-MnSO4. The substrate, NAD+, exhibits an apparent Km of 500 microM, and the activity of the enzyme is inhibited by four chemical classes of inhibitors: nicotinamides, methylxanthines, thymidine and aromatic amides. The inhibitors are effective in the following increasing order: nicotinamide less than 3-aminobenzamide less than thymidine less than 5-methylnicotinamide less than theophylline less than m-methoxybenzamide less than theobromine. The enzyme activity is also inhibited by some DNA-binding anti-malarial drugs.

Studies on autoantibodies to poly (adenosine diphosphate-ribose) in SLE and other autoimmune diseases.

Sera from 41 patients with systemic lupus erythematosus (SLE), 87 controls with various diseases, and 30 normal subjects were examined for poly (adenosine diphosphate-ribose) and ds DNA binding. Elevated levels of poly (ADP-ribose) binding were found in 73% of the SLE patients compared with 58% who had raised ds DNA binding. In a further study of 160 sera from 27 patients with SLE, levels of antipoly (ADP-ribose) antibodies were shown to correlate with clinical activity better than either anti-ds DNA or ss DNA antibodies.

The significance of antibodies to poly(adenosine diphosphate-ribose) in systemic lupus erythematosus.

Poly(adenosine diphosphate-ribose) and ds-DNA binding activity have been measured in thirty-nine systemic lupus erythematosus (SLE) sera, nineteen rheumatoid arthritis sera, fourteen sera from non-SLE rheumatic and non-rheumatic diseases and in ten normal sera. Antibodies to poly(ADP-ribose) were found only in the SLE and in three SLE-like rheumatic diseases. Anti-DNA antibodies, on the other hand, were found not only in the SLE and SLE-like diseases, but also in rheumatoid arthritis and chronic active hepatitis. Estimation of poly(ADP-ribose) binding was, therefore, more specific for, and more discriminatory of SLE from other diseases, than the estimation of ds-DNA binding. The results indicate that the estimation of poly(ADP-ribose) binding in serum may be more useful in the diagnosis of SLE than the presently employed estimation of DNA binding using the Amersham kit. DNA-anti-DNA immune complexes are detected in some of the SLE sera after deoxyribonuclease I digestion, confirming earlier reports of the existence of circulating DNA-anti-DNA complexes in SLE patients. Snake venom phosphodiesterase treatment of some of the SLE sera also resulted in increased poly(ADP-ribose) binding activity, suggesting the existence of poly(ADP-ribose)-anti-poly(ADP-ribose) immune complexes in the circulation of SLE patients. This observation raises the possiblity that poly(ADP-ribose) immune complexes may play some part in the pathogenesis of some cases of SLE.