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Biomedical subjects

D Brauer

Publications and source records attributed to D Brauer.

35 records · Page 2Linked to original sources
PubMed1982

Alkaline phosphodiesterase I and alkaline phosphatase I in plasma membranes of herpes simplex virus type 1 transformed hamster cells.

Plasma membrane extracts from Herpes simplex virus type 1 transformed hamster embryo fibroblasts were chromatographed on Lens culinaris lectin coupled to Sepharose (LcH-Sepharose) and analysed by dodecyl sulphate polyacrylamide gel electrophoresis. Coomassie blue-staining revealed two major protein bands with apparent molecular weights of 125 000 and of about 75 000-90 000. In plasma membranes isolated from these tumor cells prior labeled with [3H]fucose or [3H]glucosamine these bands contained the highest amounts of incorporated radioactivity. Separation by LcH-Sepharose-affinity chromatography as well as metabolic labeling clearly demonstrates their glycoprotein character. The 125 000 protein coincides with alkaline phosphodiesterase I activity with a Km of 6 . 10(-4) M for TMP p-nitrophenyl ester and is competitively inhibited by UDP-N-acetylglucosamine. This enzymatic activity is also present in normal hamster embryo fibroblasts. Gel electrophoresis of the Lens culinaris lectin-binding glycoproteins from plasma membranes of normal hamster embryo fibroblasts additionally revealed a strong alkaline phosphatase activity represented by an apparent molecular weight of 150 000, while HSV1 hamster tumor cells contain only a very weak activity of this enzyme activity. HSV-lytically infected cells, however, have unchanged levels of alkaline phosphatase activity, whereas alkaline phosphodiesterase activity increases slightly.

Alkaline Phosphatase↗
PubMed1982

Subclasses of simian virus 40 large T antigen: differential binding of two subclasses of T antigen from productively infected cells to viral and cellular DNA.

Two major subclasses of simian virus 40 (SV40) large T antigen were separated by zone velocity sedimentation of crude extracts from productively infected cells. These subclasses, which have been shown to differ biologically and biochemically ( Fanning et al., 1981), sedimented at 5-6S and 14-16S. The amount of T antigen in each form was estimated by complement fixation and by immunoprecipitation of T antigen from extracts of cells chronically labeled with [35S]methionine. Each form of T antigen was tested for specific binding to end-labeled restriction fragments of SV40 DNA using an immunoprecipitation assay. The 5-6S and 14-16S forms of T antigen both bound specifically to DNA sequences in the SV40 HindIII C fragment. The sequences required for binding both forms were localized in the same 35-bp region of the origin. However, significant differences in binding activity and affinity for specific and nonspecific DNA were demonstrated. These properties suggest that T antigen subclasses may serve different functions in the lytically infected cell.

Animals↗
PubMed1982

Metabolism of trans-Aconitic Acid in Maize : II. Regulatory Properties of Two Compartmented Forms of Citrate Dehydrase.

Kinetics of two molecular forms of K-dependent citrate dehydrase in maize (Zea mays L.) are reported. The isozymes, designated CD I and CD II, were found to be compartmented in mitochondria and cytosol, respectively.CD I exhibited hyperbolic kinetics with respect to both citrate and potassium with K(m) 2.3 and 12 millimolar, respectively. Maximum velocity was 0.38 micromole of trans-aconitic acid per minute per milligram protein. The pH optimum was 7.2. trans-aconitic synthesis by CD I is regulated by both citrate concentration and pH.CD II exhibited hyperbolic kinetics with respect to citrate (K(m) 0.6 millimolar) but sigmoidal kinetics with respect to potassium. trans-aconitic acid synthesis by CD II is regulated by potassium. This may account for the positive correlation between leaf potassium and trans-aconitic acid in certain grasses (Clark 1968 Crop Sci 8: 165).

Journal Article↗
PubMed1982

Subclasses of simian-virus-40 large tumor antigen. Partial purification and DNA-binding properties of two subclasses of tumor antigen from productively infected cells.

Two major subclasses of simian virus 40 tumor antigen were prepared from productively infected monkey cells. These subclasses can be distinguished by their sedimentation properties: one tumor antigen form sediments at 5-6S and the other at 14-16S. The DNA-binding properties of these subclasses were investigated by two different experimental procedures. In the first procedure, the DNA binding of subclasses of crude tumor antigen, separated by zone velocity sedimentation, were assayed by immunoprecipitation of the DNA-protein complexes. In the second procedure, the two tumor antigen forms were partially purified by column chromatography and DNA binding was tested in a filter binding assay. Both procedures gave comparable results. (a) The 5-6-S and the 14-16-S tumor antigen bound specifically to a DNA restriction fragment containing the viral genome control regions. (b) At low salt concentrations, both subclasses bound to specific and to nonspecific DNA sequences; competition experiments in the presence of nonspecific DNA showed, however, that the affinity of both tumor antigen forms for the viral genome control region was at least 10-fold higher than their affinity for nonspecific DNA sequences. (c) The binding of the 5-6-S subclass to viral control region DNA was optimal at 60-80 mM NaCl while specific DNA binding of the 14-16-S form was optimal at 150-200 mM NaCl; however, binding of the 14-16-S form to nonspecific DNA sequences was also more resistant to high salt concentrations than that of the 5-6S form. (d) Both tumor antigen forms bound well to specific and to nonspecific DNA at pH 6-6.5; with increasing pH values, binding to nonspecific DNA decreased while binding to specific DNA reached an optimum at pH 7-7.5. Binding of the 14-16-S form to viral origin DNA was more resistant to pH values above 7.5 than binding of the 5-6-S form.

Animals↗
PubMed1981

Microtubules and microfilaments in HSV-Infected rabbit-kidney cells.

In rabbit kidney cells infected with strains of Herpes simplex virus producing either cell-rounding or polycaryocytosis. Vinblastine induced paracrystals. This could be shown by phase-contrast- and electron-microscopy. Infections were done under one-step-growth conditions or at low MOI. 90 per cent noninfected cells contained stress fibers as detected by Servablue R250-staining. Shortly after recruitment into polycaryocytes, stress fibres of normal length appearing in criss-cross arrangement can be seen in the periphery of these cells. Later they polymerize to very long fibers and finally they are partially destroyed. The time of destruction depends on the MOI employed. By using Actinomycin D and/or Cycloheximide as blocking agents, it could be shown that polymerization of microfilaments correlates in time with giant cell formation. In view of the fact that the virus synthesis is accompanied in parallel by a special rearrangement of microfilaments as well as polycaryocytosis, both these processes have to be considered as caused by early (and late ?) protein-synthesis (beta-/gamma-proteins) but not as induced by "very-early" proteins (alpha-proteins).

Animals↗
PubMed1981

Adenylic acid: deoxythymidine 5'-phosphotransferase: evidence for the existence of a novel herpes simplex virus-induced enzyme.

BHK (dPyK-) cells infected with herpes simplex virus type 1 (HSV-1) contain a virus-induced deoxythymidine (dThd)-phosphorylating enzyme. This enzyme uses AMP as phosphate donor and is called AMP :deoxythymidine 5'-phosphotransferase (or kinase). The enzyme was purified over 1300-fold and was found to be specific for an AMP substrate. It can thus be distinguished from virus-specific deoxypyrimidine kinase (dPyK). It is shown that the two substrates AMP and dThd participate in the reaction at a 1 : 1 molar ratio; the Km for AMP was 2 X 3 muM and for dThd it was 2 X 1 muM. The mol. wt. of the enzyme was estimated to be between 110 000 (by glycerol gradient centrifugation) and 90 000 (by gel filtration). For optimum activity, the phosphotransferase required an alkaline pH, and 37 degrees C; the activation energy of the reaction was 18 450 cal/mol. The appearance of the enzyme after infection parallels that of viral DNA synthesis-related functions.

Adenosine Monophosphate↗
PubMed1981

Metabolism of trans-Aconitic Acid in Maize : I. PURIFICATION OF TWO MOLECULAR FORMS OF CITRATE DEHYDRASE.

Trans-aconitate synthesis via citrate dehydrase was determined in crude extracts of maize (Zea mays L.) coleoptiles. Two molecular forms of this enzyme were purified by substrate-specific elution from DEAE-cellulose, ammonium sulfate precipitation, and gel filtration. Each molecular form migrates as a single band in isoelectric focusing. Gel filtration and sodium dodecyl sulfate electrophoresis provided evidence that one enzyme form is composed of four 80,000-dalton subunits while the other is composed of two 60,000-dalton subunits. There was no evidence of proteolytic conversion of the large to the small molecular weight form when the former was incubated with either the 15,000(g) supernatant or with proteases. The data indicate that the two molecular forms of citrate dehydrase are isozymes.

Journal Article↗
PubMed1977

[Neuromyotonia syndrome (author's transl)].

In addition to the 19 cases of neuromytonia syndrome previously published, one further observation by the author is presented. The symptoms for neuromyotonia are an involuntary tensing of the musculature with impairment of movement, fasciculation and myokymia as well as specific electromyographic criteria. These symptoms are causes by a functional disturbance in the peripheral nervous system. They can be considerably improved by administering phenytoin and carbamazepine.

Aged↗
PubMed1976

Primary structure of protein L10 from the large subunit of Escherichia coli ribosomes.

The complete primary structure of protein L10 from the large subunit of the Escherichia coli ribosome has been determined. L10 is composed of 165 residues and has the amino acid composition: Asp6, Asn3, Thr9, Ser6, Glu14, Gln4, Pro5, Gly9, Ala33, Val15, Met5, Ile5, Leu15, Tyr3, Phe6, His1, Lys12, Arg13 and Cys1. The molecular weight of L10 is 17 738. The amino acid sequence was determined by a combination of automated Edman degradation of the intact protein in a modified Beckman sequentor and sequencing peptides obtained from digestions with trypsin, themolysin, Staphylococcus aureus protease and chymotrypsin. Further information was obtained from cyanogen bromide fragments and peptides resulting from digestion with trypsin after protection of the epsilon-amino groups of the lysine residues with exo-cis-3,6-endoxo-delta4-tetrahydrophthalic anhydride (ETPA).

Amino Acid Sequence↗