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Biomedical subjects

B M Torrelio

Publications and source records attributed to B M Torrelio.

8 recordsLinked to original sources
PubMed1989

Methoxatin (PQQ), coenzyme for copper-dependent amine and mixed-function oxidation in mammalian tissues.

The newly discovered coenzyme PQQ can now be measured at picomole levels with redox cycling methods developed in our laboratory. PQQ-peptides have been obtained from digests of the copper quinoenzymes, diamine oxidase, lysyl oxidase and dopamine-beta-hydroxylase. PQQ is present in egg yolk and milk, suggesting its immediate availability for developing embryos and newborn animals. We suggest that PQQ, when exposed in traumatized, ischemic, inflammed or pathological tissues, may catalyze the formation of large amounts of superoxide and should be considered as a source of oxidative stress when planning pharmacotherapeutic intervention. PQQ and quinoproteins play a role in the redox metabolism and structural integrity of cells and tissues.

Amines↗
PubMed1988

The amplified detection of free and bound methoxatin (PQQ) with nitroblue tetrazolium redox reactions: insights into the PQQ-locus.

Porcine kidney diamine oxidase, a PQQ-enzyme, can be directly measured by formazan production with putrescine and nitroblue tetrazolium. This cyclic reaction in air is unaffected by superoxide dimutase, suggesting a two electron transfer between substrate-reduced PQQ-locus and nitroblue tetrazolium, without intermediate formation of superoxide. With albumin-bound PQQ and detergent-exposed PQQ-loci, glycine can be oxidized by PQQ and electrons repetitively transferred through PQQ-sites to nitroblue tetrazolium, the rate of formazan production detecting picomoles of exposed PQQ-locus. Exposed PQQ-loci are also reducible with NaCNBH3. Nitroblue tetrazolium, reoxidizes the reduced PQQ-locus with formazan production. These experiments suggest that the PQQ-locus of quinoproteins contains a [ketone-ketoimine in equilibrium with ketoamine] redox center.

Amine Oxidase (Copper-Containing)↗
PubMed1987

Effect of hydroxyorganoboranes on synthesis, transport and N-linked glycosylation of plasma proteins.

Utilizing a recently developed method (Boradeption) for transferring water-insoluble hydroxyorganoborane compounds into the cells, we observed inhibition of protein synthesis by three of these compounds and inhibition of secretion of plasma proteins by four of them in human hepatoma HepG2 cells. These effects were specific in that the cell viability was not affected and an increase in protein catabolism was not observed. Three compounds caused a compound-specific alterations in the electrophoretic mobility of secreted glycoproteins due to underlying changes in the N-linked carbohydrate moieties. Results presented suggest a potential new source of cellular probes.

Blood Proteins↗
PubMed1987

The formation and stability of the hypusine containing protein in Chinese hamster ovary cells.

Hypusine-containing protein identified as eukaryote initiation-translation factor 4D was labeled with [14C]spermidine in logarithmically growing Chinese hamster ovary cells. Radioautography of the cellular proteins separated by polyacrylamide gel electrophoresis showed the label in a single protein of 18000 Mr. Time course analysis showed that this protein remained undegraded for up to 72 hours after its synthesis. Radioactivity present in the amino acid hypusine, isolated after acid hydrolysis, remained constant during the same period of time. These results indicate that the hypusine-containing protein has a long half-life.

Animals↗
PubMed1984

Hydralazine inhibition of the post-translational hydroxylation of deoxyhypusine, a polyamine-derived amino acid.

Logarithmically growing Chinese hamster ovary cells, cultured in the presence of [1,4-14C]putrescine, synthesize a protein(s) containing the unusual amino acid hypusine [N epsilon-(4-amino-2-hydroxybutyl)lysine]. This protein was separated and identified by two-dimensional gel electrophoresis and fluorography. The labeled hypusine isolated from an acid hydrolysate of the cell protein by ion exchange chromatography was identified by oxidative degradation and analyses of the products. Hydralazine, one of the most frequently prescribed drugs for the treatment of moderate to severe hypertension, added to the culture, resulted in the accumulation of a protein(s) containing the precursor amino acid deoxyhypusine [N epsilon-(4-aminobutyl)lysine]. Demonstration of this intermediate and its subsequent conversion to hypusine suggests that the synthesis occurs in several steps, one of these involving a hydroxylation reaction which can be inhibited by hydralazine.

Animals↗
PubMed1984

Cellular proliferation and hypusine synthesis.

Hypusine (N(-)-(4-amino-2-hydroxybutyl) lysine), a spermidine-dependent post-translational protein modification, is synthesized by various mammalian cells in culture. Experiments described in this paper demonstrated a relationship between rates of cellular growth and the synthesis of hypusine. Cells that divide at fast rates have a high rate of hypusine synthesis. In kinetic experiments, a positive relationship is evident between the rates of protein, DNA and hypusine synthesis. Cells seeded at high density, growing non-exponentially, synthesized less hypusine than logarithmically growing cells seeded at low density. Slowing the growth rate of cells by modification of the external milieu also results in a decreased rate of hypusine synthesis. These results provide additional evidence of the association of hypusine with cell proliferation in cultured cell lines and suggest a possible role for this unusual post-translational modification in the complex macromolecular events leading to cellular growth.

Animals↗
PubMed1982

Modulation of purine synthesis and phosphoribosylpyrophosphate content in human fibroblasts at different population doublings.

Human diploid fibroblasts of embryonic origin which display the limited lifespan phenomenon, respond to purine base deprivation with a large accumulation of phosphoribosylpyrophosphate when studied at early population doubling levels. This suggests that the purine salvage enzymes are the main consumers of phosphoribosylpyrophosphate in such cells. There is a strong positive correlation between the rate of de novo purine synthesis and the phosphoribosylpyrophosphate content, consistent with its role in the first and rate-limiting reaction of de novo purine synthesis. With increasing population doublings, the cells become less responsive to purine base deprivation; the phosphoribosylpyrophosphate does not increase significantly and a lower rate of de novo purine synthesis is observed. As the rate of cell replication decreases with serial passages, it becomes apparent that such cells appropriately adjust the concentration of phosphoribosylpyrophosphate, thereby controlling the rate of purine synthesis according to their needs for cellular growth.

Cell Line↗