Ornithine decarboxylase activity in extracts of phytohaemagglutinin-stimulated human lymphocytes is rapidly and extensively inhibited by additions of micromolar concentrations of putrescine or spermidine to the culture medium. This inhibition is not due to feedback inhibition of the enzyme by putrescine, spermidine or their metabolites. Inhibition is dependent on the continuation of protein syn...

The substrate specificity and kinetic mechanism of spermidine N1-acetyltransferase from rat liver was investigated using a highly purified (18 000-fold) preparation from the livers of rats in which the enzyme was induced by treatment with carbon tetrachloride (1.5 ml/kg body wt. 6h before death). The enzyme catalysed the acetylation of spermidine, spermine, sym-norspermidine, sym-norspermine, N...

In this study, we determined whether the calcium-dependent protein kinase (PKC) signaling pathway is involved in the improvement of fear memory reconsolidation induced by the intrahippocampal administration of spermidine in rats. Male Wistar rats were trained in a fear conditioning apparatus using a 0.4-mA footshock as an unconditioned stimulus. Twenty-four hours after training, animals were re...

Putrescine (1,4-diaminobutane), the product of the decarboxylation of ornithine, is a precursor of the polyamines spermidine and spermine. After administration in uiuo of radiolabeled ornithine or putrescine, changes in specific activity of putrescine, spermidine, and spermine have been assessed in normal and regenerating liver and in brain. In both normal liver and in brain, after labeling wit...

We extend the scope of nanometer distance measurements based on coupled pairs of gold nanoparticles, or plasmon rulers, to individual RNA molecules. These sensors were used to monitor the influence of spermidine on the cleavage kinetics of RNA by ribonuclease A. Time-resolved cleavage experiments of individual RNA plasmon rulers reveal transiently stabilized RNA sub-populations at increased spe...

protein aggregation is a serious problem for both biotechnology and cell biology. diseases such as prion misfolding, alzheimer’s, and other amyloidosis are phenomena for which protein aggregation in our living cells is of considerable relevance. human lysozyme has been shown to form amyloid fibrils in individuals suffering from nonneuropathic systemic amyloidosis, all of which have point mutati...

In this study, we demonstrate and elucidate how spermidine carbon dots (Spd-CDs) enhance tomato tolerance under heat stress (45 °C).

Polyamine biosynthesis in intact cells can be exquisitely controlled with exogenous polyamines through the regulation of rate-limiting biosynthetic enzymes, particularly ornithine decarboxylase (ODC). In an attempt to exploit this phenomenon as an antiproliferative strategy, certain polyamine analogues have been identified [Porter, Cavanaugh, Stolowich, Ganis, Kelly & Bergeron (1985) Cancer Res...

Ornithine decarboxylase (ODC) is feedback regulated by polyamines. ODC antizyme mediates this process by forming a complex with ODC and enhancing its degradation. It has been reported that polyamines induce ODC antizyme and inhibit ODC activity. Since exogenous polyamines can be converted to each other after they are taken up into cells, we used an inhibitor of S-adenosylmethionine decarboxylas...