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Biomedical subjects

K Murray

Publications and source records attributed to K Murray.

At least 181 records · Page 10Linked to original sources
PubMed1980

Genetic engineering: possibilities and prospects for its application in industrial microbiology.

A wide range of techniques is now available for the construction of hybrid DNA molecules comprising components from disparate species. Transfer of segments of DNA from other organisms, and especially eukaryotes, to Escherichia coli permits their preparation in quantities sufficient for detailed analysis of their structure and mechanism of expression. This information could be exploited to enhance the quantity or quality of polypeptide products from bacterial cells. Greatly increased yields of bacterial enzymes have been obtained in this way in several instances. The approaches that have been pioneered with bacteria are currently being applied to higher organisms. Much work is in progress with yeasts, in which transformation has been successfully demonstrated, with animal viruses and cells in culture and with some plant systems and offers the promise of wider application of genetic engineering in the not too distant future.

Bacteria↗
PubMed1980

The isolation and characterization of a sequence-specific endonuclease from Anabaena subcylindrica.

An endonuclease, AsuI, was isolated from extracts of Anabaena subcylindrica on the basis of gel-electrophoretic analysis of digests of bacteriophage-lambda DNA with the paritally purified extracts. The enzyme requires Mg2+, but no other cofactors. Endonuclease AsuI recognizes the interrupted tetranucleotide sequence: (Formula: see tex), and breaks the phosphodiester bonds indicated by the arrows to leave single-stranded trinucleotide projections at the 5'-termini of the DNA fragments.

Bacteriophage lambda↗
PubMed1980

The nucleotide sequences recognized by endonucleases AvaI and AvaII from Anabaena variabilis.

Determination of the 5'-terminal sequences flanking all the individual cleavage sites for endonuclease AvaI in bacteriophage-lambda DNA has shown that this enzyme recognizes the hexanucleotide sequences: (Formula: see text), This sequence is cut as shown by the arrows to give single-stranded 5'-tetranucleotide protrusions (cohesive ends). Endonucleases SmaI, XhoI and XmaI recognize different symmetrical subsets of this sequence and provide independent evidence for the occurrence of these subsets at particular endonuclease-AvaI cleavage sites in the bacteriophage-lambda genome. Further evidence for this structure came from the demonstration that DNA fragments generated by endonuclease AvaI can be ligated to form a discrete set of larger molecules and from nearest-neighbor analysis which showed that cytosine residues occurred at the 3'-side of cleavage points. The observation that endonuclease AvaII recognized a subset of the sites recognized by AsuI [Hughes, Bruce & Murray (1979) Biochem. J. 185, 59-63[ led to the deduction that AvaII recognize the pentanucleotide sequence: (Formula: see text), and breaks internucleotide bonds at the positions indicated by the arrows.

Bacteriophage lambda↗
PubMed1979

Hepatitis B virus genes and their expression in E. coli.

A composite DNA sequence of regions of hepatitis B virus, determined from a series of recombinant plasmids, reveals the genes for the surface antigen and the core antigen of the virus. The sequence of the core antigen shows it to be a DNA binding protein. The core antigen gene is expressed in Escherichia coli and when injected into rabbits the bacterial product induces antibodies which react with core antigen isolated from human sources.

Amino Acids↗
PubMed1977

Lambdoid phages that simplify the recovery of in vitro recombinants.

Derivatives of phage lambda are described for use as vectors for fragments of DNA generated with the HindIII and EcoRI restriction enzymes. With some vectors, hybrid molecules are recognised by a change from a turbid to a clear plaque morphology resulting from the insertion of a fragment of DNA into the lambda gene coding for the phage regressor. Other vectors contain a central, replaceable fragment of DNA which imparts a readily recognisable phenotype. This central fragment may include either a gene for a mutant transfer RNA (suppressor) or a part of the lacZ gene of E. coli able to complement a lacZ host. The appropriate lacZ host and indicator plates permit the ready distinction between recombinant and vector phages by the colour of the plaques.

Coliphages↗
PubMed1977

Packaging recombinant DNA molecules into bacteriophage particles in vitro.

Recombinant phage genomes made in reactions with purified enzymes may be recovered directly by packaging into phage heads in vitro. The process is efficient and nonselective and offers containment in initial stages of handling recombinant DNA. Ligase [poly(deoxyribonucleotide):poly-(deoxyribonucleotide) ligase (AMP-forming), EC 6.5.1.1] reaction products can recombine with endogenous phage DNA during packaging, but UV-irradiation eliminates the biological activity of the endogenous DNA.

Coliphages↗