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Biomedical subjects

U C Knopf

Publications and source records attributed to U C Knopf.

9 recordsLinked to original sources
PubMed1978

Molecular cloning of the gene region coding for the chloroplast rRNA of Euglena gracilis.

E. gracilis chloroplast DNA Bam fragments E and D, coding for rRNA were cloned separately using the plasmid pBR 322 as vector and E. coli as host. The newly constructed recombinant plasmids EgcKS 8 and EgcKS 11 (containing the Bam HI fragments E and D respectively) were analysed and characterized by gel electrophoresis, electronmicroscopy and analytical ultracentrifugation.

Animals↗
PubMed1976

Studies on the bacteriophage PS8 of Agrobacterium tumefaciens (Smith and Townsend) Conn: physico-chemical properties of its DNA.

DNA from the bacteriophage PS8 was extracted and purified. The buoyant density was determined was 1.716 cm3/g. The guanine-cytosine content was calculated to be 57%. DNA molecules which looked like circles were found among linear strands in an electron-microscopic study. With an endonuclease from Streptomyces albus G the DNA was digested to 19 fragments, with molecular weights ranging from 600 to 7,400 daltons. The molecular weight of the DNA was determined to be 38.8 X 10(6) daltons +/- 8.7%.

Bacteriophages↗
PubMed1975

A new two-dimensional gel electrophoresis system for the analysis of complex protein mixtures: application to the ribosome of E. coli.

A new method for two-dimensional polyacrylamide gel electrophoresis of proteins is described. The method, illustrated here by its application for the analysis of ribosomal proteins of E. coli, has a high resolving power. The proteins S15 and S16 can be resolved either following alkylation or under reducing conditions. This was not possible with urea gel systems previously employed. The method should be advantageous in the identification of the components of dimers formed with the reagent methyl 4-mercaptobutyrimidate. An additional advantage of the new method is that both dimensions are run at an acidic pH. For ribosomal proteins it is therefore unnecessary to either polymerize the protein sample in the middle of the first dimension disc gel or to electrophorese two samples with opposite polarity.

Bacterial Proteins↗
PubMed1975

The ribosomes of the Novikoff tumor cells: isolation, general properties and electrophoretic analysis of the protein moiety.

The ribosomes from Novikoff tumor and rat liver cells were extracted, purified and analyzed. The isolated ribosomes are active in Poly-U directed Poly-Phe synthesis. Sucrose density gradient centrifugation showed that the Novikoff tumor cells contained, in contrast to liver cells, almost no polysomes. The ribosomal proteins from the ribosomes were extracted and subsequently analyzed by gel electrophoresis. No differences between the ribosomal proteins of the normal and neoplastic cells could be detected by one-dimensional sodium dodecyl sulfate gel electrophoresis. Two-dimensional urea gel electrophoresis showed great similarities between the ribosomal proteins of the two kinds of cells. However some differences could be detected.

Cell Line↗
PubMed1974

The nucleoside triphosphate-ribonucleic acid nucleotidyltransferase (EC 2.7.7.6) of Agrobacterium tumefaciens (Smith and Townsend) Conn. Purification and properties of the enzyme from the tumorigenic strain B6806.

The RNA nucleotidyltransferase (RNA polymerase) of the plant-tumorigenic bacterium Agrobacterium tumefaciens was purified. The method involves the disruption of the bacterial cells with glass beads in a Waring Blendor, treatment with DEAE-cellulose, fractionation with (NH(4))(2)SO(4), protamine sulphate precipitation, DEAE-cellulose column chromatography and either glycerol-gradient centrifugation or phosphocellulose chromatography. The subunit structure of the highly purified enzyme is similar to, although not identical with, the RNA nucleotidyltransferase of Escherichia coli. It can be described as beta', beta, chi(1) and alpha (mol.wts. 160000, 150000, 98000, and 41000+/-10% respectively). chi(1) is the temporary designation for a protein subunit, which might have the same functions as the sigma subunit in E. coli. The enzyme of A. tumefaciens is rifampicin-sensitive, has a temperature optimum in vitro of 41+/-1 degrees C and a pH optimum of 8.2+/-0.1. Mg(2+) and Mn(2+) are activators. The enzyme transcribes with different efficiencies artificial, viral, bacterial, plant and animal templates.

Ammonium Sulfate↗