Calf thymus ribonuclease H IIa activity lacks ribonuclease H specificity.

Less purified fractions of ribonuclease H IIa activity of calf thymus display divalent cation-dependent ribonuclease H activity and divalent cation-independent ribonuclease activity. Because the ratio of the two enzyme activities does not change during successive chromatographic procedures, we suggest that ribonuclease H IIa activity is indeed able to degrade both ssRNA and the RNA moiety of RNA.DNA-hybrids. Ribonuclease H IIa activity can therefore be differentiated from calf thymus ribonuclease H I and H IIb by its lack of ribonuclease H specificity. The native molecular mass of ribonuclease H IIa activity is between 23 and 28 kDa. Under denaturing conditions a 23 kDa-protein band copurifies with the enzyme activity suggesting that this enzyme is monomeric.     

Calf thymus ribonuclease H IIa activity lacks ribonuclease H specificity

Summary Less purified fractions of ribonuclease H IIa activity of calf thymus display divalent cation-dependent ribonuclease H activity and divalent cation-independent ribonuclease activity. Because the ratio of the two enzyme activities does not change during successive chromatographic procedures, we suggest that ribonuclease H IIa activity is indeed able to degrade both ssRNA and the RNA moiety of RNA·DNA-hybrids. Ribonuclease H IIa activity can therefore be differentiated from calf thymus ribonuclease H I and H IIb by its lack of ribonuclease H specificity. The native molecular mass of ribonuclease H IIa activity is between 23 and 28 kDa. Under denaturing conditions a 23 kDa-protein band copurifies with the enzyme activity suggesting that this enzyme is monomeric.     

The cytotoxicity of eosinophil cationic protein/ribonuclease 3 on eukaryotic cell lines takes place through its aggregation on the cell membrane

Human eosinophil cationic protein (ECP)/ ribonuclease 3 (RNase 3) is a protein secreted from the secondary granules of activated eosinophils. Specific properties of ECP contribute to its cytotoxic activities associated with defense mechanisms. In this work the ECP cytotoxic activity on eukaryotic cell lines is analyzed. The ECP effects begin with its binding and aggregation to the cell surface, altering the cell membrane permeability and modifying the cell ionic equilibrium. No internalization of the protein is observed. These signals induce cell-specific morphological and biochemical changes such as chromatin condensation, reversion of membrane asymmetry, reactive oxygen species production and activation of caspase-3-like activity and, eventually, cell death. However, the ribonuclease activity component of ECP is not involved in this process as no RNA degradation is observed. In summary, the cytotoxic effect of ECP is attained through a mechanism different from that of other cytotoxic RNases and may be related with the ECP accumulation associated with the inflammatory processes, in which eosinophils are present. Received 26 October 2007; accepted 23 November 2007     

Degradation of ribosomal RNA from Escherichia coli by ribonuclease U2 and in vitro transcription of "RNA-fragments" into complementary DNA]

Under well defined conditions ribosomal RNAs purified from Escherichia coli can be degraded by ribonuclease U2 giving rise to RNA fragments of 60--70 nucleotides. In vitro, these fragments are efficiently transcribed into a complementary DNA by DNA polymerase RNA dependent, partially purified from extracts of E. coli. In vivo, "RNA-fragments-U2" inhibit the development of plant tumors.     

Presence of a protein disulfide isomerase (EC 5.3.4.1) in wheat germ]

The presence of a protein disulfide isomerase (rearrangease) in wheat embryo has been demonstrated by its ability in reactivating randomly cross-linked ribonuclease. This activity requires a dialysable cofactor; after dialysis, the activity is recovered by addition of reduced glutathione. The enzyme can be precipitated by 70% saturation ammonium sulfate.     

Class I and class II ribonuclease H activities in Crithidia fasciculata (Protozoa).

The protozoan Crithidia fasciculata contains two different ribonuclease H activities. These enzymes display similar physical and biochemical characteristics to their homologues in higher eukaryotes, for instance calf thymus class I and class II ribonuclease H. Class I ribonuclease H of lower and higher eukaryotes can be activated by Mg2(+)- and Mn2(+)-ions. However, the presence of Mn2(+)-ions is inhibitory for the Mg2(+)-dependent class II ribonuclease H activity of Crithidia fasciculata and calf thymus. The protozoan class I-homologue enzyme appears to be serologically related to the class I ribonuclease H of calf thymus.     

Cellular contaminants and structural proteins of Rous sarcoma virus (RSV), studied by polyacrylamide gel electrophoresis]

The number of polypeptides in highly purified preparations of RSV, of two different subgroups, produced in culture, has been compared to the polypeptides present in the supernatant of uninfected cultures and processed in identical manner. The analysis of PAGE-SDS shows that from 13 to 18 polypeptides present in viral preparations may be cellular contaminants. Fewer contaminating polypeptides are found in the myeloblastosis virus purified from plasma of Chicken.     

Involvement of ribonuclease in the interactions of macrophages and fibroblasts in experimental silicosis

Summary Decreased ribonuclease activity in the supernatant from silica-treated macrophages is associated with the enhanced protein synthesis in granulation-tissue slices incubated in this supernatant, and with the decreased degradation of polysomes in granuloma slices and of polysomes isolated from the granulation tissue. The phagocytized silica particles adsorb ribonuclease and perhaps other proteins and thus remove them from the macrophage supernatant.For financial support we are grateful to the Association of Finnish Life Assurance Companies and to the Medical Research Council in Finland.     

The eosinophil ribonucleases

The eosinophil ribonucleases, eosinophil-derived neurotoxin (EDN/RNase 2) and eosinophil cationic protein (ECP/RNase 3) are two closely related proteins with intriguing functional and evolutionary properties. While both EDN and ECP maintain the structural and catalytic residues typical of the RNase A superfamily, the role of ribonuclease activity in the physiologic function of these proteins remains unclear. The biochemistry and physiology of EDN, ECP and the recently discovered ribonuclease k6 (RNase 6) will be reviewed in this chapter.     

Class I and class II ribonuclease H activities inCrithidia fasciculata (protozoa)

Summary The protozoanCrithidia fasciculata contains two different ribonuclease H activities. These enzymes display similar physical and biochemical characteristics to their homologues in higher eukaryotes, for instance calf thymus class I and class II ribonuclease H. Class I ribonuclease H of lower and higher eukaryotes can be activated by Mg²⁺- and Mn²⁺- ions. However, the presence of Mn²⁺-ions is inhibitory for the Mg²⁺-dependent class II ribonuclease H activity ofCrithidia fasciculata and calf thymus. The protozoan class I-homologue enzyme appears to be serologically related to the class I ribonuclease H of calf thymus.     

Activity of two components of serum ribonuclease under conditions of physical exercise.

Serum ribonuclease activity before and after physical exercise in healthy persons was estimated. It is found that a work load of 6000 kgm/5 min increased ribonuclease activity measured at pH 8.5 and decreased the activity of the same enzyme measured at pH 7.0 in the presence of Zn SO4. The observed changes were more pronounced in untrained than in trained persons.     

Activity of two components of serum ribonuclease under conditions of physical exercise

Summary Serum ribonuclease activity before and after physical exercise in healthy persons was estimated. It is found that a work load of 6000 kgm/5 min increased ribonuclease activity measured at pH 8.5 and decreased the activity of the same enzyme measured at pH 7.0 in the presence of ZnSO₄. The observed changes were more pronounced in untrained than in trained persons.     

Distinction of influenza viruses of different host cell origin

Influenza A viruses grown in different animal or human cells retain their antigenic make-up as tested by the usual immunological assays. With the aid of a Sambucus nigra (L.) extract containing its lectins the viruses can be distinguished after one single passage in a different cell type by a change in their hemagglutinating properties. Binding of such lectins to influenza viruses may be a means for a more subtle classification, relating to the host cell origin of the virus.     

Effect of exercise on ribonuclease activity in rat skeletal muscle.

Distribution of ribonuclease activity (measured at pH 7.6) in subcellular fractions of homogenates of rat skeletal muscle was investigated in sedentary animals and after 8 weeks running program. Training increased ribonuclease activity (expressed as units of enzyme per g of muscle protein). There was no increase in nuclear fraction, but in both cytoplasmic and mitochondrial fractions the RNA-ase activity increased 42% and 45% respectively.     

Distinction of influenza viruses of different host cell origin

Summary Influenza A viruses grown in different animal or human cells retain their antigenic make-up as tested by the usual immunological assays. With the aid of aSambucus nigra (L.) extract containing its lectins the viruses can be distinguished after one single passage in a different cell type by a change in their hemagglutinating properties. Binding of such lectins to influenza viruses may be a means for a more subtle classification, relating to the host cell origin of the virus.     

Acrosomal hydrolases in buffalo spermatozoa.

Buffalo sperm acrosome resembles its counterpart in other species, being rich in hydrolytic enzymes. Of the enzyme activities estimated, acid phosphatase, beta-N-acetylglucosaminidase and hyaluronidase were low compared to those of ram semen. However, the aryl sulphatase activity was high. GOT activity estimated in sperm preparation may not be of acrosomal origin.     

Inclusion of Gross virus cell surface associated antigen in liposomes]

The Gross virus associated cell surface antigen GCSAa was extracted from (C58NT)D cells by solubilization of membranes with detergent and partially purified. This antigen was entraped in liposomes. Absorption experiments of the cytotoxic activity towards EmaleG2 cells of a W/Fu anti (C58NT)D serum showed the presence of the antigen at the surface of sensibilized liposomes.     

Non-A non-B hepatitis virus: demonstration of a double antigenic and structural kinship with hepatitis B virus

Major antigenic identity has been demonstrated by immunodiffusion between the Ag described by Shirachi and confirmed by us (NANB/e) in the serum on non A non B hepatitis and the HBe/3 specificity of hepatitis B virus (HBV). A second Ag (NANB/c) linked to the core of a new virion morphologically similar to HBV and also associated with ADN polymerase activity as recently described, has been identified and purified from an infected liver. This NANB/c Ag also cross reacts with HBc Ag. These results confirm that HBV and the NANB virus defined here belong to the same new class of DNA viruses.     

Demonstration of measles virus antigens in osteoclasts in Paget's disease of bone]

The first results of histo-immunological studies on biopsies in Paget's bone disease strongly favour the presence of antigenic material of viral origin in osteoclasts. Measles virus may play a role in the etiology of Paget's bone disease.     

Die Veränderungen der Succinodehydrase-Aktivität in Detroit-6 (VA) Zellen,infolge der Infektion mit demHepatitis-infectiosa-Virus

Summary The inhibitory action ofHepatitis infectiosa virus on the SDH activity of Detroit-6 (VA) cell lines was investigated. The full inhibition of the SDH activity took place at the end of the third day after the infection. As this phenomenon precedes the cytopathogenetic effect of viral infection, it may be of some help in the early detection of the infection.