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Biomedical subjects

M W Lambert

Publications and source records attributed to M W Lambert.

43 records · Page 3Linked to original sources
PubMed1982

Differential inhibition of transcription of DNA by melanoma chromosomal proteins.

Histones and 4 nuclear nonhistone protein fractions (NHP1-4) were extracted from nuclei of a Cloudman mouse melanoma cell line (NCTC 3960, CCL 53) and tested for their ability to bind to DNA and influence transcription. The histones and NHP fractions showed different binding affinities for DNA, with the histones and NHP1 exhibiting the highest affinity. The NHP fractions differentially affected both the rate of RNA synthesis and the size of RNA transcribed. NHP1 which inhibited RNA synthesis to the greatest extent, inhibited synthesis of all sizes of RNA except for major peaks of 28S and 8S RNS and discrete minor peaks of 7S, 6S, 5S, and 4S RNS. Histones markedly enhanced the effect of NHP1 on RNA synthesis. These results suggest that there are nonhistone proteins in Cloudman melanoma nuclei which have a high affinity for DNA and which may be involved in the regulation of transcription.

Animals↗
PubMed1979

Purification and properties of a nuclear DNA endonuclease from HeLa S3 cells.

An endonuclease that can act on calf thymus DNA and circular doublestranded phage PM2 DNA has been isolated from HeLa S3 cell chromatin. Approximately 200-fold purification was achieved by a sequence of subcellular fractionation, differential NaCl solubility and chromatography on CM-Sephadex, DEAE-cellulose and hydroxyapatite, and isoelectric point is pH 5.1 +/- 0.2. Divalent cations are necessary for its activity and the enzyme is heat inactivated at 60 degrees C. The enzyme activity is sensitive to caffeine and sulfhydryl reacting compounds. The molecular weight, determined by gel filtration and SDS gel electrophoresis, is approx. 22 000.

Caffeine↗
PubMedDate not supplied

Enhancement of assays of activities of endonucleases on defined substrates by Poisson and non-Poisson combinatoric analysis.

Assay of endonuclease activity, as performed in most laboratories, depends upon change in form of small, defined substrate molecules, with a secondary computation required to obtain a determination of enzyme activity. We now explore the assumptions inherent in these computations and provide a series of equations that permit more accurate determinations of enzyme activity from assays of this type. These equations allow information to be obtained not only from substrate fractions left uncleaved by the endonuclease, upon which conventional systems rely, but also from products cleaved by the enzyme. Some information yielded by these equations is unobtainable using conventional methods of analysis.

DNA↗