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Biomedical subjects

R F Murphy

Publications and source records attributed to R F Murphy.

At least 217 records · Page 12Linked to original sources
PubMed1977

Comparison of non-biospecific effects in immunoaffinity chromatography using cyanogen bromide and bifunctional oxirane as immobilising agents.

Polypeptide antigen, glucagon, antibodies to glucagon and non-immune globulins were immobilised on agarose using CNBr and a bifunctional oxirane. Irrespective of the ligand immolilised, positively charged groups introduced to conjugates by CNBr caused electrostatic interactions with impurities and soluble biospecific ligands. Solvents required for elution of bound antibodies and antigens were more strongly deforming when immunoaffinity conjugates were prepared with CNBr than with the oxirane. This is attributed to compound affinity resulting from reinforcement of biospecific by non-biospecific interactions. Strongly deforming solvents were still required for oxirane conjugates, however, when antibodies had high affinity for antigen.

Antibodies↗
PubMed1977

Physical properties of chemically acetylated rat liver chromatin.

The physical properties of rat liver chromatin and nucleosomes acetylated with acetic anhydride were examined in order to clarify the mechanism by which chemical acetylation of histones increases template activity in vitro [Marushige, K. (1976) Proc. Natl. Acad. Sci. USA 73, 3937-3941]. Acetylation was found to have dramatic effects on the magnesium solubility, nuclease sensitivity, thermal denaturation, and sedimentation of chromatin and nucleosomes. The significance of the results to models of gene activation and chromatin replication is considered.

Acetylation↗
PubMed1976

Avoidance of strongly chaotropic eluents for immunoaffinity chromatography by chemical modification of immobilized ligand.

The need for chaotropic eluents in immunoaffinity chromatography is a consequence of the high affinities of antibodies towards their antigens. This affinity is decreased and elution of antiglucagon antibodies from a column of immobilized glucagon can be achieved under mild conditions when the steric complementarity to the antibody binding site is perturbed by selective chemical modification of the hormone. The effects of reaction with 2-hydroxy-5-nitrobenzyl bromide, tetranitromethane and hydrogen peroxide have been studied. Conversely, treatment of immobilized antibodies with 2-hydroxy-5-nitrobenzyl bromide facilitates the elution of glucagon during immunoaffinity chromatography. The general implications of these results are discussed.

Animals↗
PubMed1975

Structure of transcriptionally active chromatin.

Rat-liver chromatin has bee fractionated into transcriptionally active and inactive regions [Gottesfeld et al. (1974) Proc. Nat. Acad. Sci. USA 71, 2193-2197] and the distribution of nuclease-resistant complexes in these fractions has been investigated. About half of the DNA of both fractions is resistant to attack by tne endonuclease DNase II. The nuclease-resistant structures of inactive chromatin are DNA-histone complexes (v-bodies) which sediment at 11-13 S. Template-active chromatin yields two peaks of nuclease-resistant nucleoprotein. These complexes sediment at 14 and 19 S, and contain DNA, RNA, histone, and nonhistone chromosomal proteins. Polyacrylamide gel electrophoresis reveals a complex pattern of chromatin proteins, suggesting that the complexes are heterogeneous in composition.

Animals↗