Phosphorylation and biosynthesis of high molecular weight proteins of tumor nuclear matrix.

Our previous studies showed a predominance of high molecular weight protein group in tumor nuclear matrices. Contrary to normal cells, proteins of this group are preferentially phosphorylated. Phosphoproteins of hepatoma nuclear matrix are selectively subjected to rapid proteolysis.

An unusual NAD(P)H-dependent O2-.-enerating redox system in hepatoma 22a nuclei.

Nuclear membranes from many tumors contain an unusual redox chain discovered originally in the Hepatoma 22a nuclear membranes which catalyzes superoxide dismutase-sensitive adrenaline oxidation to adrenochrome in the presence of either NADPH or NADH as electron donor, the reaction being inhibited by cyanide and azide. This redox chain can reduce anthracycline antitumor antibiotics adriamycin and carminomycin to their free radical states under anaerobic conditions. Evidence has been obtained for a higher stability of the carminomycin radical as compared to that of adriamycin.

DNAaseI-hypersensitive minichromosomes of SV40 possess an elastic torsional strain in DNA.

Previously, we have shown that DNA in a small fraction (2-5%) of SV40 minichromosomes was torsionally strained and could be relaxed by treating minichromosomes with topoisomerase I. This fraction was enriched with endogeneous RNA polymerase II (Luchnik et al., 1982, EMBO J.

Superoxide dismutase-sensitive, NAD(P)H-dependent reduction of oxygen by the membrane-bound redox chains of liver microsomes and hepatoma nuclei in the presence of adrenaline.

Evidence has been obtained that the NAD(P)H-dependent "generation of superoxide radicals" by various types of membrane bound redox chains, as studied by the adrenaline method, does not occur in the absence of adrenaline. Studies of the oxygen uptake associated with the NAD(P)H-dependent adrenaline co-oxidation confirm the presence of an unusual cyanide-sensitive electron transfer system in the nuclear membranes from Hepatoma 22a. This redox chain contains a b-type cytochrome which resembles cytochrome b5.

Visualization of reactive oxygen species formation by phagocytizing macrophages.

Activated peritoneal macrophages exhibiting phagocytosing capacity produced an electron-dense precipitate of formazan in contact sites of macrophage plasmalemma and phagocytosed yeast cells. No production of formazan occurred, when non-opsonized latex particles were ingested by macrophages. Formazan precipitation could be prevented by anaerobiosis but not by addition of cyanide.