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Biomedical subjects

J Hurwitz

Publications and source records attributed to J Hurwitz.

At least 235 records · Page 13Linked to original sources
PubMed1974

Involvement of two protein factors and ATP in in vitro DNA synthesis catalyzed by DNA polymerase 3 of Escherichia coli.

The in vitro conversion of single-stranded DNA from bacteriophage fd to duplex structures depends on E. coli RNA polymerase, DNA polymerase III, riboand deoxyribonucleoside triphosphates, Mg(+2), spermidine or DNA-unwinding protein of E. coli, and two additional protein factors, referred to here as Factors I and II. These two factors are also essential for dTMP incorporation catalyzed by DNA polymerase III and dependent on poly(dA).oligo(dT) primer-template. In the latter reaction, there is an absolute dependency on ATP or dATP.

Adenine Nucleotides↗
PubMed1974

Conversion of phiX174 viral DNA to double-stranded form by purified Escherichia coli proteins.

The E. coli proteins that catalyze the conversion of varphiX174 single-stranded DNA to duplex DNA have now been purified extensively. The reaction depends on dnaB, dnaC(D), dnaE, and dnaG gene products, DNA elongation factors I and II, E. coli DNA binding protein, and two additional E. coli proteins, replication factors X and Y. DNA synthesis by these proteins requires varphiX174 viral DNA, dNTPs, Mg(+2), and ATP. The product synthesized is full-length linear varphiX174 DNA. The reaction has been resolved into two steps. The first step involves the interaction of ATP and varphiX174 DNA with dnaB and dnaC(D) gene products, E. coli DNA binding protein, and replication factors X and Y in the absence of dNTPs. Subsequent dNMP incorporation requires the addition of DNA polymerase III, DNA elongation factors I and II, dnaG gene product, and dNTPs.

Adenosine Triphosphate↗
PubMed1974

Association of DNA-dependent and -independent ribonucleoside triphosphatase activities with dnaB gene product of Escherichia coli.

Preparations of E. coli dnaB gene product contain ribonucleoside triphosphatase activity that is stimulated 10-fold by DNA. The products of the triphosphatase activity are nucleoside diphosphates and P(i). The dnaB complementing activity in the varphiX174 DNA-dependent system and these triphosphatase activities copurify over the last 20-fold of an extensive (about 40,000-fold) purification procedure. Acrylamide gel electrophoresis of the purified material shows a single band of protein coincident with eluted dnaB complementing and DNA-dependent and -independent nucleoside triphosphatase activities.

Adenosine Triphosphatases↗
PubMed1974

The in vitro synthesis of avian myeloblastosis viral RNA sequences.

Isolated nuclei, prepared from myeloblasts of chicks infected with avian myeloblastosis virus, synthesize RNA sequences present in avian myeloblastosis viral RNA. These sequences are also formed during transcription of chromatin, isolated from myeloblasts, by DNA-dependent RNA polymerases purified from Escherichia coli or calfthymus. In the latter case, transcription is alpha-amanitin sensitive. Formation of hybrids between RNA and avian myeloblastosis virus DNA probes has been monitored by the combined use of ribonucleases A, T(1), and H, and ribonucleases specific for single strands.

Animals↗
PubMed1973

Studies on in vitro DNA synthesis. Isolation of DNA B gene product from Escherichia coli.

Formation of duplex DNA from varphiX174 single-stranded DNA by extracts of E. coli was previously shown to require the gene product of dna B. Using as an assay the stimulation of varphiX174 DNA-dependent synthesis in inactivated extracts of dna B temperature-sensitive cells, we purified the dna B gene product from wild-type E. coli as well as from a dna B temperature-sensitive mutant. The dna B temperature-sensitive gene product is more thermolabile than its wild-type counterpart.

Adenosine Triphosphatases↗
PubMed1973

Mechanism of action of ribonuclease H isolated from avian myeloblastosis virus and Escherichia coli.

Purified preparations of RNA-dependent DNA polymerase isolated from avain myeloblastosis virus contain RNase H activity. Labeled ribohomopolymers are degraded in the presence of their complementary deoxyribopolymer, except [(3)H]poly(U).poly(dA). The degradation products formed from [(3)H]poly(A).poly(dT) were identified as oligonucleotides containing 3'-hydroxyl and 5'-phosphate termini, while AMP was not detected. The nuclease has been characterized as a processive exonuclease that requires ends of poly(A) chains for activity. Exonucleolytic attack occurs in both 5' to 3' and 3' to 5' directions.RNase H has also been purified from E. coli. This nuclease degrades all homoribopolymers tested in the presence of their complementary deoxyribopolymers to yield oligonucleotides with 5'-phosphate and 3'-hydroxyl termini. E. coli RNase H has been characterized as an endonuclease.

Avian Leukosis Virus↗
PubMed1973

Studies on in vitro DNA synthesis. Purification of the dna G gene product from Escherichia coli.

varphiX174 DNA-dependent dNMP incorporation is temperature-sensitive (ts) in extracts of uninfected E. coli dna A, B, C, D, E, and G ts strains. DNA synthesis can be restored in heat-inactivated extracts of various dna ts mutants by addition of extracts of wild-type or other dna ts mutants. A protein that restores activity to heat-inactivated extracts of dna G ts cells has been extensively purified. This protein has also been purified from dna G ts cells and is thermolabile when compared to the wild-type protein. The purified dna G protein has a molecular weight of about 60,000, is insensitive to N-ethylmaleimide, and binds poorly to DNA. It does not stimulate heat-inactivated crude extracts of dna B, C, D, or E ts cells and lacks detectable RNA and DNA polymerase activities.

Ammonium Sulfate↗