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Biomedical subjects

K Murray

Publications and source records attributed to K Murray.

At least 217 records · Page 12Linked to original sources
PubMed1973

Nucleotide sequence analysis with polynucleotide kinase and nucleotide "mapping" methods. 5'-Terminal sequences of deoxyribonucleic acid from bacteriophages lambda and 424.

The polynucleotide kinase reaction was used in analyses of complex mixtures of oligodeoxynucleotides which were fractionated by various two-dimensional nucleotide ;mapping' procedures. Parallel ionophoretic analyses on DEAE-cellulose paper, pH2, and AE-cellulose paper, pH3.5, of venom phosphodiesterase partial digests of 5'-terminally labelled oligonucleotides enabled the sequence of the nucleotides to be deduced uniquely. A ;diagonal ionophoresis' method has been used with mixtures of nucleotides. Application of these methods to 5'-terminally labelled DNA from bacteriophage lambda gave the terminal sequences pA-G-G-T-C-G and pG-G-G-C-G. Identical 5'-terminal sequences were found with DNA from bacteriophage 424.

Adenine Nucleotides↗
PubMed1973

Polynucleotides associated with histone preparations.

Histone fractions prepared from various sources by acid extraction or by salt dissociation contained small quantities of ribo- and deoxyribo-nucleotides. These nucleotides were small and heterogeneous and were efficiently removed from histone preparations by ionexchange chromatography. They probably represent contaminants, rather than uniquely complexed nucleotides, of all the histone preparations.

Animals↗
PubMed1973

The 3'-terminal nucleotide sequences of bacteriophage lambda DNA.

Analyses of radioactive oligonucleotides in endonuclease digests of 3'-terminally labeled lambda DNA revealed the 3' terminal sequence -GTTACG for the l strand and -ACCCGCG for the r strand. These sequences, together with those previously known for the 5' cohesive ends, provide a total of 25 known base-pairs in the vicinity of the termini. When the cohesive ends are paired, the sequence between the nicks can be bisected by a 2-fold rotational axis of symmetry. Five of the first eight base-pairs, on either side of the axis, are rotationally symmetric. This symmetry may be involved in the recognition of the site by an enzyme responsible for formation of the cohesive ends.

Adenine Nucleotides↗
PubMed1973

Measurement of methaemalbumin in plasma.

Using the method of Chong and Owen (1967), the normal range of methaemalbumin in plasma was 0 to 0.6 mg/100 ml, expressed as milligrams of haematin per cent. Previous results, using the method of Shinowara and Walters (1963), reported a normal range of 0 to 8.0 mg/100 ml, but it was expressed as milligrams of haemoglobin percent. The conversion factor from the Shinowara method is as follows: mg haematin % = mg haemoglobin % x 0.04.

Heme↗
PubMed1972

The deoxyribonucleic acid modification enzyme of bacteriophage P1.

The bacteriophage P1 modification enzyme, assayed by the specific methylation of unmodified bacteriophage 82 DNA, has been purified 500-fold from a bacteriophage P1 lysogen of Escherichia coli. The enzyme catalyses the incorporation of approximately 20-24 methyl groups per bacteriophage 82 DNA molecule. The sole product of methylation is 6-methylaminopurine. Methylation of unmodified bacteriophage DNA confers protection against a challenge by purified bacteriophage P1 restriction enzyme. The pH optimum is 6.0-6.25: the apparent K(m) for S-adenosyl-l-methionine is 5x10(-6)m.

Ammonium Sulfate↗
PubMed1970

Nucleotide 'maps' of digests of deoxyribonucleic acid.

Various digests of (32)P-labelled DNA were examined by two-dimensional ionophoresis on cellulose acetate and DEAE-cellulose paper. The products from digestion with pancreatic deoxyribonuclease and Neurospora crassa endonuclease were qualitatively closely similar, but very complex, and were used to investigate the mapping behaviour of nucleotides in various ionophoretic systems. Ionophoresis on DEAE-cellulose paper in triethylamine carbonate, pH 9.7, followed by ionophoresis in the second dimension at pH1.9 gave high resolution of nucleotides in very complex mixtures and permitted the fractionation of larger quantities than is possible on cellulose acetate. High resolution of nucleotides in compact spots was obtained with two-dimensional ionophoresis on cellulose acetate and AE-cellulose paper, a system that is a useful supplement to those based on DEAE-cellulose paper.

Cellulose↗
PubMed1970

The dissociation of chicken erythrocyte deoxyribonuleoprotein and some properties of its partial nucleoproteins.

Histones were completely dissociated from their native complex with DNA in 2.0m-sodium chloride. Histone fractions IIb, V and I were dissociated in 1.2m-sodium chloride, fractions V and I in 0.7m-sodium chloride and fraction I in 0.45m-sodium chloride. Repeated extraction of partial dRNP (deoxyribonucleoprotein) preparations with sodium chloride of the same concentration as that from which they were prepared resulted in release of histones that previously had remained associated with the DNA of the complex. Gradual removal of histones from dRNP was paralleled by an improvement in solubility, a decrease in wavelength of the u.v.-absorption minimum, and a fall in sedimentation coefficient of the remaining partial dRNP. X-ray diffraction patterns of partial dRNP preparations showed that removal of histone fractions I and V from dRNP did not destroy the super-coil structure of the dRNP, but further removal of histones did. Infrared spectra of partial dRNP preparations showed that in native dRNP histone fraction I was present in the form of extended, isolated polypeptide chains, and that the other histone fractions probably contain a helical component that lies roughly parallel to the polynucleotide chains in the double helix and an extended polypeptide component that is more nearly parallel to the DNA helix axis. An analysis of the sedimentation of partial dRNP preparations on sucrose gradients showed that native dRNP consists of DNA molecules each complexed with histone fractions of all types.

Amino Acids↗