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Biomedical subjects

M Chorazy

Publications and source records attributed to M Chorazy.

At least 73 records · Page 4Linked to original sources
PubMed1980

Activity of chromatin-bound protease in histone fractions from rat liver and Morris hepatoma.

Activity of chromatin-bound protease of rat liver and Morris hepatoma 7777 was studied. Proteolytic enzyme was copurified with histones during extraction of chromatin with 0.25 M HCl. Total histone was fractionated by Oliver's et al. method. Histone fractions were incubated in 0.01 M Tris-HCl buffer (pH 7.6) at 37 degrees C within different periods of time. The behavior of these fractions in polyacrylamide gel electrophoresis as well as the amounts of peptides soluble in 5% TCA released during incubation indicated that enzyme was coextracted with histone H2B only. It was shown that the activity of protease coextracted selectively with histone H2B was higher in tumor tissue than in normal liver.

Animals↗
PubMed1978

Complex of DNA with chromatin proteins investigated by isopycnic centrifugation in metrizamide.

Complexes of mouse main band DNA with a fraction of non-histone proteins (NHP), having a high affinity for DNA, in the absence or presence of histones have been investigated by gradient centrifugation in metrizamide. Two types of complexes were formed at an input ratio of NHP to DNA between 1 and 2.5. In metrizamide gradients a majority of DNA was found in the light complex (at the density of 1.14-1.16 g/cm3) even at the very high NHP to DNA ratio. When histones were present in the reaction mixture, most of the DNA was found in the heavy complex (1.19-1.21 g/cm3). The electrophoretic profiles of the proteins recovered from the heavy and light complexes were different; some fractions of nonhistone proteins were present only in the heavy component.

Animals↗
PubMed1978

Changes in cellular concentration of DNA-dependent RNA polymerases A and B during regeneration of rat liver.

1. DNA-dependent RNA polymerases A and B were solubilized from rat liver nuclei at different intervals after partial hepatectomy, and chromatographed on DEAE-Sephadex A-25. Activity of the solubilized RNA polymerases remained unchanged till 6 h after hepatectomy, then started to increase reaching a maximum (350% and 150% of control for the A and B enzyme, respectively) at the 18th hour of regeneration, and was still high at the 36th hour of regeneration. 2. RNA polymerases A and B were extracted and extensively purified from the nuclei of normal and regenerating rat liver. No marked differences in the specific activities between the analogous purified enzymes from normal and regenerating liver were observed, thus the increase in RNA polymerase activities (especially marked in the case of enzyme A) observed after partial hepatectomy is probably due to a real increase in the quantities of enzymes. 3. Concentration of RNA polymerase A in hepatocyte increases from 1.3 x 10(4) (normal liver) to 7.5 x 10(4) (18 h after hepatectomy) molecules per haploid genome. The concentration of polymerase B increases from 3.4 x 10(4) to 5.5 x 10(4) molecules per haploid genome, respectively.

Ammonium Sulfate↗
PubMed1977

Interactions of some nitro-derivatives of substituted 9-aminoacridine with DNA.

The mechanism of the biological activity of the 1-nitro and 2-nitro aminoacridine derivatives containing the dimethylaminopropyl side chain was studied. RNA synthesis in the isolated rat liver nuclei was only slightly influenced by both compounds. They do not differ in their ability to form an intercalative complex with DNA. Only the 1-nitro derivative exhibited strong inhibitory effect on RNA biosynthesis and caused distinct ultrastructural changes (nucleolar segregation, chromatine margination etc.) in a living cell. The 1-nitro derivative binds covalently to DNA in vivo resulting in crosslink formation. It is concluded that the biological activity of 1-nitro acridine derivatives depends more on their crosslinking activity than on their ability to intercalate into DNA.

Acridines↗
PubMed1977

Transcription of rat DNA fractions reassociated to various cOt values.

Two fractions of rat liver DNA: "intermediate" (reassociated to COt = 1 - 10(2), moleXsecX1(-1)) and "slow" (COt = 10(2) - 10(5) showed differences in template activity on transcription with E. coli RNA-polymerase. The "intermediate" fraction both in double- and single-stranded form was a better template than the "slow" one. The efficiency of transcription dropped progressively for the template obtained at COt values increasing from 10(2) to 10(6). No differences in the template activity of the "intermediate" and "slow" fractions were observed when rifampicin-resistant transcription was studied.

Animals↗
PubMed1976

Some features of DNA-tRNA hybrids in the rat.

1. Sequences complementary to rRNA in rat DNA amount to 0.04% which corresponds to about 300 rRNA genes per haploid genome. 2. Purified DNA-rRNA hybrids had a DNA: rRNA weight ratio of about 1.1:1. Their melting temperature estimated on hydroxyapatite column was 75-80 degrees C. In CsCl gradients hybrids banded at 1.728 g/cm3 as compared to 1.699 g/cm3 for bulk DNA. 3. Length distribution histogram of DNA-rRNA hybrid molecules visualized by electron microscopy revealed that most of them possessed a length of 0.2-0.5 mum which corresponds to 4 X 10(5)-1 X 10(6) daltons, i.e. 670-1600 nucleotide pairs. 4. DNA sequences complementary to rRNA are localized on the heavy shoulder of the main band at a CsCl density of 1.709 g/cm3, and in a DNA fraction which re-associates at a Cot=10(-1)-10(2).

Animals↗
PubMed1975

Complexes of derivatives of 1-nitro-9-aminoacridine with DNA.

Substituted 1-nitro-9-aminoacridine derivatives were shown to inhibit RNA and to a lesser extent protein synthesis in cultured human cells. Complex formation between the compounds studied and DNA were considered to be responsible for their cytostatic action. Two types of complexes differing in their binding forces were found. The biological activity of the studied compounds seems not to be dependent on the existence of a positive charge on the acridine ring.

Acridines↗
PubMed1975

Isolation and properties of poly(A)-containing RNA from the cytoplasm of rat liver cells.

1. The described technique for preparative isolation of poly(A)-containing RNA by complexing with poly(U)-cellulose and elution at 45 degrees C, is simple, reproducible, and the poly(U)-cellulose preparation is suitable for repeated use. 2. The poly(A)-containing RNA isolated from the poly(U)-cellulose complex is still contaminated by ribosomal RNA which can be removed by recomplexing. The purified preparation is heterogeneous on polyacrylamide-gel electrophoresis and is located over the region from 5-6S to 28S. Poly(A) segments of cytoplasmic RNA show heterogeneous size distribution. 3. In acidic medium, the poly(A) segments form ordered double-stranded structure. 4. The rapid labelling of rat liver and fibroblast cytoplasmic poly(A)-containing RNAs and their base composition resemble closely the corresponding properties of mRNA.

Adenine Nucleotides↗