Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polydeoxycytidylic acid (poly dC) was incubated with excess acrolein. A Nensorb 20 nucleic acid purification cartridge was used to bind the polymeric material in the poly dC/acrolein reaction mixture. The non-polymeric material eluted from this column had a UV absorbance four times higher than that of the control. The fluorescence spectrum of the eluted material did not correspond to that of unmodified cytosine. Separate aliquots of the reaction mixture were digested to deoxynucleotide 3'-monophosphates by incubation with micrococcal nuclease and spleen phosphodiesterase. The products were converted to 32P-labeled deoxynucleotide 3',5'-bisphosphates by incubation with T4 polynucleotide kinase and excess [gamma-32P]ATP. The 3'-monophosphate was selectively removed by incubation with nuclease P1. Two-dimensional thin-layer chromatography (TLC) on polyethyleneimine cellulose (PEI)-cellulose and detection of 32P-labeled deoxynucleotide 5'-monophosphates by autoradiography failed to provide evidence for the formation of an acrolein adduct of deoxycytidine 5'-monophosphate. When acrolein-modified deoxycytidine 3'-monophosphate was 32P post-labeled, a new product, which co-chromatographed with UV markers synthesized by reaction of acrolein with deoxycytidine 5'-monophosphate, was detected. These data show that acrolein-modified deoxycytidine 3'-monophosphates are substrates for 32P labeling by T4 polynucleotide kinase and are stable under the assay conditions employed. The inability to detect the acrolein-modified nucleotides after reaction with poly dC in vitro suggests that the modified bases are lost from poly dC by cleavage of the N-glycosyl bond resulting in the formation of an abasic site.
Cancer Lett 1988 May
PMID:Implications for the formation of abasic sites following modification of polydeoxycytidylic acid by acrolein in vitro. 337 Jun 25

Monoclonal antibodies were prepared to nuclear nonhistone proteins from a 2-aminoacetyl fluorine-induced transplantable rat hepatocellular carcinoma. These antibodies recognized a total of six distinct antigens as revealed by molecular weight analysis. Studies of antigen specificity with respect to various tissues, tumors, cultured cells, and oncodevelopmental stages indicated that these nuclear species could be divided into two categories. Four antigens were classified as tumor related since they were significantly enriched in tumor tissue as compared to tissues of the normal adult rat. The remaining two antigens were detected only in tumors and transformed cells; one, only in certain hepatomas. Thus, these antigens were classified as tumor specific. As an initial step toward elucidating the function of these proteins, each antigen was isolated by immunoaffinity chromatography, radioiodinated in situ, and analyzed for the ability to bind DNA. Three antigens were positive for DNA binding, and one of these was selectively released from tumor nuclei with the transcriptionally active chromatin upon digestion with micrococcal nuclease. The implications of these results for the possible functional contribution of the six tumor antigens to transformation is discussed.
Cancer Res 1988 Oct 01
PMID:Isolation and analysis of hepatoma nuclear proteins using monoclonal antibodies. 341 5

Sodium cyanate is a selective in vivo inhibitor of protein synthesis in a variety of mammalian tumor cells without a corresponding effect on the normal tissues of tumor-bearing animals. The in vivo decrease of protein synthesis observed 4 h post-NaOCN i.p. administration in the murine P388 leukemia cell cannot be explained by decreased amino acid pools in the mouse peritoneal cavity. In addition, the decrease in protein synthesis observed with NaOCN in isolated P388 cells was shown not to be secondary to (a) alterations in the kinetics of amino acid transport or (b) effects on total nucleotide pools. The incorporation of [14C]phenylalanine in P388 cell-free lysates from NaOCN-pretreated mice was significantly decreased to approximately 55% of control lysates in the presence of exogenous amino acids. The addition of exogenous calf liver tRNA to the lysates did not alter this result. However, no difference was observed in polyuridylic acid-directed [14C]phenylalanine incorporation into polypeptides in micrococcal nuclease-treated P388 lysates from NaOCN-pretreated or control mice. Quaternary initiation complex (48S) formation and mRNA synthesis were found to be significantly decreased by 35 and 38%, respectively, in P388 cells from NaOCN-pretreated mice. DNA synthesis was decreased by 66% of control at 1 h and 62% at 4 h post-NaOCN i.p. administration. No apparent effect with NaOCN was observed on total RNA synthesis in P388 cells. These results suggest that the decrease in P388 cell protein synthesis observed with NaOCN in vivo appears to be due to alterations manifested in the synthesis of cellular mRNA and protein synthesis initiation processes. NaOCN does not appear to affect the P388 cell ribosomal machinery, tRNA, or protein synthesis elongation processes.
Cancer Res 1987 Oct 01
PMID:Mechanism of decrease of protein synthesis by sodium cyanate in murine P388 leukemia cells. 362 Nov 95

The DNA in nuclei from rat-ascites hepatoma (AH) was rather resistant to endogenous endonucleolytic attack (autodigestion), compared with that in nuclei from normal rat liver (RL). In contrast, by micrococcal nuclease, the DNA in AH nuclei was cleaved in the same manner as in RL nuclei. A 0.6 M NaCl extract was prepared from RL or AH nuclei and subjected to Sephadex G-100 filtration. The resulting-nuclease fraction was separated further into two nuclease fractions, I and II, by CM-Sephadex column chromatography. The activity ratio of II to I was 7.1 for the RL and 2.0 for the AH nuclei. Moreover, the activity of fraction II from the AH nuclei was rather low, compared with that from the RL nuclei. Regenerating-liver nuclei from the normal rat were also assayed in the same way. The results obtained were very similar to those from the AH nuclei. In addition, each of fractions, I and II, cleaved pBR322 DNA of superhelical form; in other words, each had endonucleolytic ability.
Cancer Lett 1985 Dec
PMID:An endodeoxyribonuclease activity in nuclei from rat-ascites hepatoma. 407 93

We have examined aspects of the interaction of cycled microtubule protein preparations with 35S-labeled mouse DNA tracer in a competition system with unlabelled competitor E. coli or mouse DNA. The nitrocellulose filter binding assay was used to measure interaction by scintillation counting. DNA molecular weight affected the levels of filter retained 35S-labelled mouse tracer DNA. Filter retention levels increased if 35S-labelled mouse DNA tracer size was increased, and the filter binding level decreased if competitor DNA size was increased. There was a sizeable, reproducible difference in the 35S-labelled mouse DNA tracer binding level of about 1% when E. coli or mouse DNA competitors were compared. Mouse DNA more effectively competed with 35S-labelled mouse DNA for microtubule protein binding than did E. coli DNA, suggesting that a small class of higher-organism DNA sequences interacts very strongly with microtubule protein. From other studies we know this to be the MAP fraction (Marx, K.A. and Denial, T. (1984) in The Molecular Basis of Cancer (Rein, R., ed.), Alan R. Liss, New York, in the press; and Villasante, E., Corces, V.G., Manso-Martinez, R. and Avila, J. (1981) Nucleic Acids Res. 9, 895-908). We find that this difference in competitor DNA strength is qualitatively similar under high-stringency conditions (0.5 M NaCl, high competitor [DNA]) we developed for examining high-affinity complexes. Under high-stringency conditions we isolated 1.2% and 0.6% of 35S-labelled mouse DNA at 4200 and 350 bp respective sizes as nitrocellulose filter bound DNA-protein complexes. At both molecular weights these high-affinity DNA sequences, isolated from the filters, were shown to be significantly enriched in repetitive DNA sequences by S1 nuclease solution reassociation kinetics. The kinetics are consistent with about a 4-fold mouse satellite DNA enrichment as well as enrichment in other repetitious DNA sequence classes. The high molecular weight filter-bound DNA samples were sedimented to equilibrium in CsCl buoyant density gradients and found to contain primarily mouse satellite DNA density sequences (1.691 g/cm3) with some minor fractions at other density positions (1.670, 1.682, 1.705, 1.740, 1.760 g/cm3) similar to those observed by our laboratory in previous investigations of micrococcal nuclease-resistant chromatin (Marx, K.A. (1977) Biochem. Biophys. Res. Commun. 78, 777-784). That the high-affinity microtubule-bound DNA was some 3-5-fold enriched in mouse satellite sequences was demonstrated by its characteristic BstNI restriction enzyme cleavage pattern.
 ...
PMID:High-affinity microtubule protein-higher organism DNA complexes. Many-fold enrichment in repetitive mouse DNA sequences comprised of satellite DNAs. 639 51

Oligonucleosomes were isolated from [14C]thymidine-labeled HeLa cells by digestion of the nuclei with micrococcal nuclease and were then alkylated with [3H]methylnitrosourea. Nucleosome core particles were also prepared by further digestion of the oligonucleosomes. The distribution of 3H-labeled methyl groups in the linker versus the core DNA was established by a determination of 3H:14C ratios in oligonucleosome and core DNA. The ratios in the core DNA of 145 and 165 base pair DNA fragments were 5.2 and 5.4, respectively, while the ratio in the oligonucleosomal DNA was 8.2. Assuming an equal mixture (as determined) of 145 and 165 base pair fragments of DNA in the 185 base pair repeat, the relative concentration of 3H methyl groups in the linker versus the core DNA was 4.2. Thus, 45% of the 3H methyl groups were in the linker DNA, and 55% were in the core DNA. Some shielding of the DNA was evident during alkylation. The concentrations of alkyl groups on the linker and core DNA were 67 and 12% of that found on free DNA alkylated under comparable conditions. No evidence for preferential shielding of the major or minor groove was observed. The purified 3-methyladenine DNA glycosylase I of Escherichia coli released approximately 37% of the 3-methyladenine from the linker DNA and 13% from the core DNA. The limited enzymatic removal of 3-methyladenine in vitro compared to the efficient removal in vivo suggests that conformational changes of the oligonucleosome and core structure must occur for total repair.
Cancer Res 1983 Dec
PMID:Release of 3-methyladenine from linker and core DNA of chromatin by a purified DNA glycosylase. 664 May 26

Distribution of DNA-bound 4-nitroquinoline 1-oxide (4NQO) and repair-synthesized DNA after treatment with 4NQO in chromatin was investigated with human diploid fibroblast WI-38. Cells were incubated with [3H] 4NQO, and sites of binding on chromatin DNA were analyzed either by sensitivity to micrococcal nuclease or DNase I, or by fractionation of chromatin on sucrose gradient centrifugation. The results showed that 4NQO preferentially binds to DNA of linker region of chromatin, but the binding was random with respect to transcriptional activity of chromatin. The distribution of repair-synthesized DNA in chromatin damaged by 4NQO was also studied by similar experiments. [3H] Thymidine incorporated into repaired DNA was more sensitive to nucleases, but distributed almost equally among DNAs of chromatin subfractions with different transcriptional activity.
Cancer Lett 1981 Nov
PMID:Distribution of DNA-bound carcinogen 4-nitroquinoline 1-oxide and of repair-synthesized DNA in chromatin of WI-38 cells. 679 24

An estrogen-responsive mouse Leydig cell tumor line (Tumor 124958) has been shown to contain only a low-affinity binder for estradiol in the cytosol fraction. This differed from the putative estrogen receptor in terms of its hormone-binding specificity as well as affinity. In addition, the possibility that an estrogen receptor-like molecule exists in the nuclei even without hormonal stimuli was examined using purified nuclei. Scatchard plot analyses showed that these nuclei possessed a large amount of estrogen binder having a high affinity for estradiol and diethylstilbestrol. The content of this nuclear binding component was not diminished by using molybdate, a potent inhibitor for receptor activation, and in vitro incubation of collagenase-dispersed cells with estradiol did not cause significant increase in the number of nuclear binding sites when compared with the values obtained by direct incubation of isolated nuclei with estradiol. These results support the view that this nuclear estrogen binder is not due to artificial migration of the cytosol receptor into nuclei during homogenization. The characterization of this nuclear binding component under cell-free conditions revealed that its affinity for estradiol in Mg2+-containing buffer was temperature dependent (Kd 3 nM at 30 degrees and 12 nM at 0 degrees) without significant alteration in the number of maximum binding sites. Introduction of a chelating agent (ethylenediaminetetraacetate) into the buffer system abolished the temperature effect on the affinity, resulting in high affinity for estradiol at both low and high temperatures. These Mg2+ and temperature effects were reversible. In addition, when compared with putative nuclear estrogen receptors, this nuclear binding was observed to be relatively resistant to high salt or micrococcal nuclease treatments in relation to solubilization from nuclei. However, trypsin digestion was found to result in a marked decrease in the nuclear binding sites, indicating that this unique nuclear binding component contains a protein unit(s). These results suggest the possibility that this tumor line contains a unique unoccupied nuclear estrogen binder which might be able to transmit estrogen signals to tumor cell nuclei with regard to tumor growth.
Cancer Res 1983 Sep
PMID:Characterization of a unique nuclear estrogen-binding component in an estrogen-responsive mouse Leydig cell tumor. 687 50

The antigenicity and composition of chromatins differ markedly in chromatin preparations obtained by different procedures. Rat Novikoff hepatoma chromatin (NC) obtained by the "salt precipitation" and the micrococcal nuclease digestion procedures using significant levels of EDTA and NaCl each shows a common complement fixation (CF) capacity, exceeding chromatin preparations obtained from normal rat liver when tested with rabbit antisera raised to dehistonized NC. In contrast, "structured" NC preparations, which have been postulated to retain a native physical conformation, show minimal CF capacity when tested with the same antiserum but show high CF following elution of histones. While further progressive elution of non-histone proteins (NHPs) did not alter the CF capacity per unit DNA, the completely separated DNA and NHP fractions each showed minimal CF. The data suggest that the antigens detected in the CF assay predominantly represent an artifactual but specific complex of DNA and NHP arising from a denaturation of the native chromatin following elution of metal ions or histones. A qualitatively similar profile of NHPs in salt-precipitated NCs shows a range of total protein/DNA ratios, suggesting that the NHPs found in chromatin preparations may not be intrinsic to the native chromatin structure.
Cancer Res 1983 Oct
PMID:Effects of divalent metal cations on composition and neoplasia-specific antigenicity of chromatins. 688 42

No differences were detected in the micrococcal nuclease or deoxyribonuclease I-solubilized (euchromatin) proteins from several preneoplastic and neoplastic mouse epithelial cell lines. Significant levels of endogenous chromatin solubilization were detected in these cell lines prior to the addition of the exogenous nucleases. The endogenous solubilization markedly reduced the susceptibility of the remaining chromatin to solubilization by micrococcal nuclease or deoxyribonuclease I. Evidence is presented which suggest that the endogenous solubilization may obscure differences in the protein components of the euchromatin fraction from these preneoplastic and neoplastic cell lines.
Cancer Biochem Biophys 1982
PMID:Euchromatin protein analysis in preneoplastic and neoplastic cell lines: effects of endogenous chromatin solubilization. 715 Oct 37


<< Previous 1 2 3 4 5 6 Next >>