Workshop on communicable disease surveillance in Europe: Is there a need for a European centre?
Weekly releases (1997–2007), 2002
A workshop will be held at the European Parliament in Brussels, on 6 November 2002, on the need a... more A workshop will be held at the European Parliament in Brussels, on 6 November 2002, on the need and possible function of a European Centre for Communicable Disease. The workshop is organised by Professor Antonios Trakatellis, rapporteur for the European Parliament on the programme of Community action in the field of public health (2003-08), in cooperation with the European Vaccine Manufacturers (EVM), a specialised group within the European Federation of Pharmaceutical Industry Associations (EFPIA).
Detection of a high molecular weight heparin binding acidic growth factor in human placenta
Biochemistry and molecular biology international, 1995
A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has be... more A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has been detected in human placenta. The protein was extracted from placenta and purified by a combination of ammonium sulfate precipitation, DE-52 anion exchange chromatography, G100 gel exclusion and heparin sepharose affinity chromatography. The molecule was shown to be monomeric after treatment with beta-mercaptoethanol, and had an acidic isoelectric point. The properties of the polypeptide described in this paper (45 kDa, Pi 4-5, monomeric, heparin binding fibroblast growth factor), suggest that it may represent an as yet undescribed growth factor.
Sialyltransferase and nucleoside diphosphatase as markers for tumor monitoring
Cancer detection and prevention, 1985
In this study we report serum sialyltransferase and nucleoside diphosphatase activities of patien... more In this study we report serum sialyltransferase and nucleoside diphosphatase activities of patients with malignant tumors of various primary sites and extent, prior to and during chemotherapy. Enzyme levels were compared to clinical and laboratory parameters. The sialyltransferase and uridine diphosphatase (UDPase) activities in samples of 43 patients with advanced ovarian cancer was four to ten fold above the normal mean value (sialyltransferase 85.1 +/- 58 pmol/hr/ml and UDPase 26.6 +/- 7.2 nmol/hr/ml). After effective chemotherapy with adriamycin and cisplatin, the enzyme activity decreased markedly. In cases of complete remission, enzyme activity decreased to the normal range. In three cases after initial response for several months a rise of both enzymes was observed before any other biochemical finding of the forthcoming relapse. Similar patterns were observed in testicular cancer (6 cases). Clinical correlation is also obvious in other tumors except malignant lymphomas. Our f...
Beta zero and beta+ thalassemia genes in northern Greece
Gene geography : a computerized bulletin on human gene frequencies
In an attempt to estimate the prevalence of beta thal zero and beta thal+ thalassemia genes in no... more In an attempt to estimate the prevalence of beta thal zero and beta thal+ thalassemia genes in northern Greece we analyzed hemoglobin samples of 32 subjects with sickle cell thalassemia (beta s/beta thal), from an area of northern Greece (Chalkidiki, 22-24E, 41-42N), where thalassemia and sickle cell disease are common. 24 subjects had no detectable Hb A and only 8 had Hb A ranging grossly between 3-5 per cent in six patients and 10-15 per cent in two patients. Thus the estimate of the relative frequency of the beta thal zero to the beta thal+ was found to be 0.75 +/- 0.077. For the beta thal+ gene, our findings are in agreement with all other Greek investigations in that it is associated with a low or very low presence of Hb A. As to frequencies, however, our findings differ significantly from results reported from other Greek investigators who examined mainly the population of Athens, and this may be explained by an uneven distribution of the various types of thalassemia genes in ...
Effect of pyridoxine deficiency on immunological phenomena
Postgraduate medical journal, 1992
Measurements of serine hydroxymethyltransferase (SHMT) in resting lymphocyte cultures showed that... more Measurements of serine hydroxymethyltransferase (SHMT) in resting lymphocyte cultures showed that the level of activity of this enzyme was very low. Under the influence of mitogenic stimuli serine hydroxymethyl-transferase activity was induced 5-20-fold. Addition in the cultures of 4-deoxypyridoxine, a potent antagonist of vitamin B6 coenzymes, concurrently with the mitogen, inhibits the induction of serine hydroxymethyltransferase. Thus deoxypyridoxine exerts its effects not only at the level of the enzyme itself by antagonizing the coenzyme but also at the level of its biosynthesis. Synchronous addition of vitamin B6 with deoxypyridoxine effectively reverses the inhibitory effects. The T helper cells of the lymphocyte culture are very sensitive to deoxypyridoxine action in contrast to T suppressor cells. The effect of phytohaemagglutinin or concanavalin A on the production of interleukin-1b, interleukin-2 and interleukin-2 receptors is profoundly affected by deoxypyridoxine. These...
DNA-dependent RNA polymerases from nuclei of T8 Guerin tumor were studied. Two enzymes were purif... more DNA-dependent RNA polymerases from nuclei of T8 Guerin tumor were studied. Two enzymes were purified several hundred times by the use of ammonium sulfate precipitation, DEAE-cellulose and phosphocellulose chromatography. One of them belongs to A(I) RNA polymerases and the second to B(II) as was established from their metal and ionic strength requirements. activity in the presence of native and denatured DNA and the resistance to a-amanitin inhibition. The quantity of class A enzyme was increased compared to B, a fact observed with most neoplastic tissues so far studied. This increase of the polymerase responsible for ribosomal RNA synthesis could probably be related to malignant transformation in animals.
The characteristics and mode of action of a single-strand-specific nuclease isolated from rat liv... more The characteristics and mode of action of a single-strand-specific nuclease isolated from rat liver endoplasmic reticulum are investigated with respect to its DNA and RNA substrates. 2. The RNase activity of the enzyme is slightly influenced by the presence of divalent cations but the DNase activity is enhanced by divalent cations particularly Mn 2+. 3. Activity is partially inhibited by the presence of EGTA; this effect is reversed most efficiently by the addition of Mn 2+. 4. The enzyme exhibits small pH dependence between pH 6-9 and maximum activity is observed at pH 7-7.5 for both DNase and RNase activities. 5. Sulfhydryl group reagents do not affect its action but histidyl group reagents exert a small but definite effect. 6. The enzyme degrades DNA and RNA endonucleolyticaHy producing fragments which possess Y-OH and 5'-phosphate termini. 7. Monomers arc not produced even after prolonged degradation. 8. The end product of poly(U)degradation ranges between two and four building blocks but the DNA product is longer probably due to considerable percentage of secondary structure.
Effect of Diet and Insulin on G6PD and H6PD Activity of Rat Liver
Animals and Environmental Fitness, 1980
Publisher Summary This chapter discusses the effect of diet and insulin on G6PD and H6PD activity... more Publisher Summary This chapter discusses the effect of diet and insulin on G6PD and H6PD activity of rat liver. It is well known that the activity of the enzymes G6PD and H6PD undergoes large changes in response to diet and insulin. It is observed that in the fasting state, cytosol G6PD and H6PD activities are low. After the animals are transferred in the standard diet, a quick mobilization of the microsomal G6PD and H6PD enzymes takes place and there is five-fold increase of the corresponding enzyme activities in the cytosol. An even greater response is provoked when the diet is supplemented by glucose. In this case, the mobilization of G6PD and H6PD is followed by de novo synthesis of these enzymes. The biosynthesis of G6PD and H6PD is even greater after insulin injection. The administration of Actinomycin causes inhibition of de novo enzyme synthesis. The changes of enzymic activity in this case are similar to those observed in the animals of the group of standard diet.
Summary Pyridoxine deficiency leads to impairment of immune responses. It appears that the basic ... more Summary Pyridoxine deficiency leads to impairment of immune responses. It appears that the basic derangement is the decreased rate of production of one-carbon units necessary for the synthesis of nucleic acids. The key factor is a pyridoxine enzyme, serine hydroxymethyltransferase. This enzyme is very low in resting lymphocytes but increases significantly under the influence of antigenic or mitogenic stimuli, thus supplying the increased demand for nucleic acid synthesis during an immune response. Serine hydroxymethyltransferase activity is depressed by deoxypyridoxine, a potent antagonist of pyridoxal phosphate, and also by known immunosuppressive or antiproliferative agents. The combination of these agents is additive. Our results lead us to suggest the following medical applications: (a) combination of deoxypyridoxine with immunosuppressive or chemotherapeutic drugs may be effective in cases of immunosuppressive therapy or organ transplantation, (b) the development of special age...
Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis, 1977
DNA-dependent RNA polymerases type A and B from rat liver nuclei were found to be inactivated by ... more DNA-dependent RNA polymerases type A and B from rat liver nuclei were found to be inactivated by a macromolecular inhibitor. This inhibitor was located mainly in the smooth rat liver endoplasmic reticulum. The extraction of this substance from smooth microsomal membranes was carried out with 0.1% sodium deoxycholate and 0.2 M (NH4)2SO4. Purification of the inhibitor was achieved by chromatography on DEAE-cellulose followed by ECTEOLAcellulose and DEAE-Sephadex chromatography. Evidence for the macromolecular nature of the inhibitor was obtained by gel filtration and heat stability experiments. The inhibitory effect was not connected with RNAase, DNAase, or with enzymic hydrolysis of the various nucleoside triphosphates acting as nucleoside triphosphatase or nucleoside triphosphate pyrophosphatase. Complete inhibition with both A and B polymerases was observed. However, polymerase A activity was more sensitive to the inhibitor. The inhibitory effect is related to the concentration of manganese and all four nucleoside triphosphates present in the assay. These data support the possibility that the inhibitor binds the Mn2+-nucleoside triphosphate complex thus preventing the substrate from reaching the enzyme site(s).
MCP-1 is a small (8-10 KDa) protein and a prototype member of the CC chemokine ß subfamily, which... more MCP-1 is a small (8-10 KDa) protein and a prototype member of the CC chemokine ß subfamily, which plays a critical role in acute and chronic inflammation. Recent evidence suggests an important role for MCP-1, MCP-2 and MCP-3 in a number of pathological states, including delayed type hypersensitivity conditions, parasitic infections and rheumatoid arthritis. Forty BALB-c mice were treated with
The effect of infra-red laser irradiation has been experimented on various biological systems and... more The effect of infra-red laser irradiation has been experimented on various biological systems and particularly in human tissues, in vitro as well as in vivo. In order to examine the influence of laser irradiation on cells of the monocytic lineage we have irradiated human peripheral blood mononuclear cells with an infra-red laser at a wavelength of 904 nm, at 2000
Specific antibodies which were raised against a single-strand-specific nuclease isolated from rat... more Specific antibodies which were raised against a single-strand-specific nuclease isolated from rat liver microsomes were used for characterizing this enzyme and determining its cellular and tissue distribution. 2. The single-strand-specific nuclease does not show any homology with other known nucleolytic enzymes. 3. It is mainly localized in microsomes and cytosol; traces of it are also found in nuclei, but it could not be detected in mitochondria. 4. Using the same specific antibodies we attempted to detect this nuclease in some other tissues which exhibit high metabolic rates, namely kidneys, heart and spleen. 5. Thus, with the aid of immunological techniques we were able to determine that at least part of the total poly(U) nucleolytic activity observed in kidney and heart is due to a nuclease immunologically identical to the enzyme under study. Kidneys were the best source for this enzyme.
The activity of liver and adipose tissue is very sensitive to changes of diet. 2. Quick changes o... more The activity of liver and adipose tissue is very sensitive to changes of diet. 2. Quick changes of G6PD activity occur almost simultaneously with the institution of new dietary conditions. 3. The activity of the enzyme reaches a new maximum level 6 hr after the beginning of the new dietary conditions and then fluctuates around this new level of activity. 4. When insulin is administrated a second phase of increase is observed after 18 hr and it is related with transcription and production of new messenger RNAs coding for G6PD.
An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was ... more An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was isolated from rat liver endoplasmic reticulum. The enzyme yields on gel chromatography four active fractions of different molecular weights ( M , 5.3 x lo4, 9 x lo4, 1.55 x lo5 and Sephacryl S-200 fraction at Vo). Each fraction contains polypeptide chains which give a single band on sodium dodecylsulphate electrophoresis ( M , 5.4 x 10"). This indicates that the enzyme is an oligomeric protein and each of its subunits exhibits the same or very similar molecular weights. Deoxyribonucleoside and ribonucleoside triphosphales can bind to the endoplasmic reticulum nuclease. Binding is enhanced in the presence of divalent cations particularly MgZf. The enzyme exhibits mainly RNase activity but can also degrade denatured DNA and D N A . RNA hybrids which contain breaks in one of the two strands. Poly(A) and mainly poly(U) are most susceptible to its nucleolytic activity whereas poly(C) is completely resistant
Workshop on communicable disease surveillance in Europe: Is there a need for a European centre?
Weekly releases (1997–2007), 2002
A workshop will be held at the European Parliament in Brussels, on 6 November 2002, on the need a... more A workshop will be held at the European Parliament in Brussels, on 6 November 2002, on the need and possible function of a European Centre for Communicable Disease. The workshop is organised by Professor Antonios Trakatellis, rapporteur for the European Parliament on the programme of Community action in the field of public health (2003-08), in cooperation with the European Vaccine Manufacturers (EVM), a specialised group within the European Federation of Pharmaceutical Industry Associations (EFPIA).
Detection of a high molecular weight heparin binding acidic growth factor in human placenta
Biochemistry and molecular biology international, 1995
A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has be... more A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has been detected in human placenta. The protein was extracted from placenta and purified by a combination of ammonium sulfate precipitation, DE-52 anion exchange chromatography, G100 gel exclusion and heparin sepharose affinity chromatography. The molecule was shown to be monomeric after treatment with beta-mercaptoethanol, and had an acidic isoelectric point. The properties of the polypeptide described in this paper (45 kDa, Pi 4-5, monomeric, heparin binding fibroblast growth factor), suggest that it may represent an as yet undescribed growth factor.
Sialyltransferase and nucleoside diphosphatase as markers for tumor monitoring
Cancer detection and prevention, 1985
In this study we report serum sialyltransferase and nucleoside diphosphatase activities of patien... more In this study we report serum sialyltransferase and nucleoside diphosphatase activities of patients with malignant tumors of various primary sites and extent, prior to and during chemotherapy. Enzyme levels were compared to clinical and laboratory parameters. The sialyltransferase and uridine diphosphatase (UDPase) activities in samples of 43 patients with advanced ovarian cancer was four to ten fold above the normal mean value (sialyltransferase 85.1 +/- 58 pmol/hr/ml and UDPase 26.6 +/- 7.2 nmol/hr/ml). After effective chemotherapy with adriamycin and cisplatin, the enzyme activity decreased markedly. In cases of complete remission, enzyme activity decreased to the normal range. In three cases after initial response for several months a rise of both enzymes was observed before any other biochemical finding of the forthcoming relapse. Similar patterns were observed in testicular cancer (6 cases). Clinical correlation is also obvious in other tumors except malignant lymphomas. Our f...
Beta zero and beta+ thalassemia genes in northern Greece
Gene geography : a computerized bulletin on human gene frequencies
In an attempt to estimate the prevalence of beta thal zero and beta thal+ thalassemia genes in no... more In an attempt to estimate the prevalence of beta thal zero and beta thal+ thalassemia genes in northern Greece we analyzed hemoglobin samples of 32 subjects with sickle cell thalassemia (beta s/beta thal), from an area of northern Greece (Chalkidiki, 22-24E, 41-42N), where thalassemia and sickle cell disease are common. 24 subjects had no detectable Hb A and only 8 had Hb A ranging grossly between 3-5 per cent in six patients and 10-15 per cent in two patients. Thus the estimate of the relative frequency of the beta thal zero to the beta thal+ was found to be 0.75 +/- 0.077. For the beta thal+ gene, our findings are in agreement with all other Greek investigations in that it is associated with a low or very low presence of Hb A. As to frequencies, however, our findings differ significantly from results reported from other Greek investigators who examined mainly the population of Athens, and this may be explained by an uneven distribution of the various types of thalassemia genes in ...
Effect of pyridoxine deficiency on immunological phenomena
Postgraduate medical journal, 1992
Measurements of serine hydroxymethyltransferase (SHMT) in resting lymphocyte cultures showed that... more Measurements of serine hydroxymethyltransferase (SHMT) in resting lymphocyte cultures showed that the level of activity of this enzyme was very low. Under the influence of mitogenic stimuli serine hydroxymethyl-transferase activity was induced 5-20-fold. Addition in the cultures of 4-deoxypyridoxine, a potent antagonist of vitamin B6 coenzymes, concurrently with the mitogen, inhibits the induction of serine hydroxymethyltransferase. Thus deoxypyridoxine exerts its effects not only at the level of the enzyme itself by antagonizing the coenzyme but also at the level of its biosynthesis. Synchronous addition of vitamin B6 with deoxypyridoxine effectively reverses the inhibitory effects. The T helper cells of the lymphocyte culture are very sensitive to deoxypyridoxine action in contrast to T suppressor cells. The effect of phytohaemagglutinin or concanavalin A on the production of interleukin-1b, interleukin-2 and interleukin-2 receptors is profoundly affected by deoxypyridoxine. These...
DNA-dependent RNA polymerases from nuclei of T8 Guerin tumor were studied. Two enzymes were purif... more DNA-dependent RNA polymerases from nuclei of T8 Guerin tumor were studied. Two enzymes were purified several hundred times by the use of ammonium sulfate precipitation, DEAE-cellulose and phosphocellulose chromatography. One of them belongs to A(I) RNA polymerases and the second to B(II) as was established from their metal and ionic strength requirements. activity in the presence of native and denatured DNA and the resistance to a-amanitin inhibition. The quantity of class A enzyme was increased compared to B, a fact observed with most neoplastic tissues so far studied. This increase of the polymerase responsible for ribosomal RNA synthesis could probably be related to malignant transformation in animals.
The characteristics and mode of action of a single-strand-specific nuclease isolated from rat liv... more The characteristics and mode of action of a single-strand-specific nuclease isolated from rat liver endoplasmic reticulum are investigated with respect to its DNA and RNA substrates. 2. The RNase activity of the enzyme is slightly influenced by the presence of divalent cations but the DNase activity is enhanced by divalent cations particularly Mn 2+. 3. Activity is partially inhibited by the presence of EGTA; this effect is reversed most efficiently by the addition of Mn 2+. 4. The enzyme exhibits small pH dependence between pH 6-9 and maximum activity is observed at pH 7-7.5 for both DNase and RNase activities. 5. Sulfhydryl group reagents do not affect its action but histidyl group reagents exert a small but definite effect. 6. The enzyme degrades DNA and RNA endonucleolyticaHy producing fragments which possess Y-OH and 5'-phosphate termini. 7. Monomers arc not produced even after prolonged degradation. 8. The end product of poly(U)degradation ranges between two and four building blocks but the DNA product is longer probably due to considerable percentage of secondary structure.
Effect of Diet and Insulin on G6PD and H6PD Activity of Rat Liver
Animals and Environmental Fitness, 1980
Publisher Summary This chapter discusses the effect of diet and insulin on G6PD and H6PD activity... more Publisher Summary This chapter discusses the effect of diet and insulin on G6PD and H6PD activity of rat liver. It is well known that the activity of the enzymes G6PD and H6PD undergoes large changes in response to diet and insulin. It is observed that in the fasting state, cytosol G6PD and H6PD activities are low. After the animals are transferred in the standard diet, a quick mobilization of the microsomal G6PD and H6PD enzymes takes place and there is five-fold increase of the corresponding enzyme activities in the cytosol. An even greater response is provoked when the diet is supplemented by glucose. In this case, the mobilization of G6PD and H6PD is followed by de novo synthesis of these enzymes. The biosynthesis of G6PD and H6PD is even greater after insulin injection. The administration of Actinomycin causes inhibition of de novo enzyme synthesis. The changes of enzymic activity in this case are similar to those observed in the animals of the group of standard diet.
Summary Pyridoxine deficiency leads to impairment of immune responses. It appears that the basic ... more Summary Pyridoxine deficiency leads to impairment of immune responses. It appears that the basic derangement is the decreased rate of production of one-carbon units necessary for the synthesis of nucleic acids. The key factor is a pyridoxine enzyme, serine hydroxymethyltransferase. This enzyme is very low in resting lymphocytes but increases significantly under the influence of antigenic or mitogenic stimuli, thus supplying the increased demand for nucleic acid synthesis during an immune response. Serine hydroxymethyltransferase activity is depressed by deoxypyridoxine, a potent antagonist of pyridoxal phosphate, and also by known immunosuppressive or antiproliferative agents. The combination of these agents is additive. Our results lead us to suggest the following medical applications: (a) combination of deoxypyridoxine with immunosuppressive or chemotherapeutic drugs may be effective in cases of immunosuppressive therapy or organ transplantation, (b) the development of special age...
Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis, 1977
DNA-dependent RNA polymerases type A and B from rat liver nuclei were found to be inactivated by ... more DNA-dependent RNA polymerases type A and B from rat liver nuclei were found to be inactivated by a macromolecular inhibitor. This inhibitor was located mainly in the smooth rat liver endoplasmic reticulum. The extraction of this substance from smooth microsomal membranes was carried out with 0.1% sodium deoxycholate and 0.2 M (NH4)2SO4. Purification of the inhibitor was achieved by chromatography on DEAE-cellulose followed by ECTEOLAcellulose and DEAE-Sephadex chromatography. Evidence for the macromolecular nature of the inhibitor was obtained by gel filtration and heat stability experiments. The inhibitory effect was not connected with RNAase, DNAase, or with enzymic hydrolysis of the various nucleoside triphosphates acting as nucleoside triphosphatase or nucleoside triphosphate pyrophosphatase. Complete inhibition with both A and B polymerases was observed. However, polymerase A activity was more sensitive to the inhibitor. The inhibitory effect is related to the concentration of manganese and all four nucleoside triphosphates present in the assay. These data support the possibility that the inhibitor binds the Mn2+-nucleoside triphosphate complex thus preventing the substrate from reaching the enzyme site(s).
MCP-1 is a small (8-10 KDa) protein and a prototype member of the CC chemokine ß subfamily, which... more MCP-1 is a small (8-10 KDa) protein and a prototype member of the CC chemokine ß subfamily, which plays a critical role in acute and chronic inflammation. Recent evidence suggests an important role for MCP-1, MCP-2 and MCP-3 in a number of pathological states, including delayed type hypersensitivity conditions, parasitic infections and rheumatoid arthritis. Forty BALB-c mice were treated with
The effect of infra-red laser irradiation has been experimented on various biological systems and... more The effect of infra-red laser irradiation has been experimented on various biological systems and particularly in human tissues, in vitro as well as in vivo. In order to examine the influence of laser irradiation on cells of the monocytic lineage we have irradiated human peripheral blood mononuclear cells with an infra-red laser at a wavelength of 904 nm, at 2000
Specific antibodies which were raised against a single-strand-specific nuclease isolated from rat... more Specific antibodies which were raised against a single-strand-specific nuclease isolated from rat liver microsomes were used for characterizing this enzyme and determining its cellular and tissue distribution. 2. The single-strand-specific nuclease does not show any homology with other known nucleolytic enzymes. 3. It is mainly localized in microsomes and cytosol; traces of it are also found in nuclei, but it could not be detected in mitochondria. 4. Using the same specific antibodies we attempted to detect this nuclease in some other tissues which exhibit high metabolic rates, namely kidneys, heart and spleen. 5. Thus, with the aid of immunological techniques we were able to determine that at least part of the total poly(U) nucleolytic activity observed in kidney and heart is due to a nuclease immunologically identical to the enzyme under study. Kidneys were the best source for this enzyme.
The activity of liver and adipose tissue is very sensitive to changes of diet. 2. Quick changes o... more The activity of liver and adipose tissue is very sensitive to changes of diet. 2. Quick changes of G6PD activity occur almost simultaneously with the institution of new dietary conditions. 3. The activity of the enzyme reaches a new maximum level 6 hr after the beginning of the new dietary conditions and then fluctuates around this new level of activity. 4. When insulin is administrated a second phase of increase is observed after 18 hr and it is related with transcription and production of new messenger RNAs coding for G6PD.
An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was ... more An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was isolated from rat liver endoplasmic reticulum. The enzyme yields on gel chromatography four active fractions of different molecular weights ( M , 5.3 x lo4, 9 x lo4, 1.55 x lo5 and Sephacryl S-200 fraction at Vo). Each fraction contains polypeptide chains which give a single band on sodium dodecylsulphate electrophoresis ( M , 5.4 x 10"). This indicates that the enzyme is an oligomeric protein and each of its subunits exhibits the same or very similar molecular weights. Deoxyribonucleoside and ribonucleoside triphosphales can bind to the endoplasmic reticulum nuclease. Binding is enhanced in the presence of divalent cations particularly MgZf. The enzyme exhibits mainly RNase activity but can also degrade denatured DNA and D N A . RNA hybrids which contain breaks in one of the two strands. Poly(A) and mainly poly(U) are most susceptible to its nucleolytic activity whereas poly(C) is completely resistant
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