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PubMed1999

Nucleotide and polyamine levels in colostrum and mature milk in relation to maternal atopy and atopic development in the children.

The prophylactic benefit of breastfeeding against atopic disease is still controversial. It seems to be limited to infants with genetic propensities to allergy in combination with late solid food introduction. Lower levels of n-3 polyunsaturated fatty acids in human milk have been related to atopy in children, stressing a non-specific role of nutritional components in the development of atopy. Nucleotides and polyamines have been related to intestinal integrity and immune function in infancy. The main sources of these nutrients are human milk nucleotides and polyamines early in life. Our aim was to study the composition of nucleotides and polyamines in colostrum and mature milk from atopic and non-atopic mothers and the relationship to sensitization against egg, milk or cat in their children during the first year of life. The nucleotide/nucleoside and polyamine levels were measured by HPLC in colostrum and in milk at 3 mo of lactation from mothers of 21 atopic and 14 non-atopic children. Among the mothers, 10 were atopic and 25 non-atopic. The nucleotides cytidine monophosphate (CMP), uridine monophosphate (UMP), adenosine monophosphate (AMP) and guanosine monophosphate (GMP) and the nucleosides cytidine and uridine were detected in human milk. In colostrum, CMP dominated, and the levels increased in mature milk, while the levels of the other compounds remained constant. The nucleotide/nucleoside composition was similar in colostrum from all mothers independent of the development of sensitization in their babies, except for the higher cytidine levels in mature milk from atopic mothers of atopic babies, as compared to healthy mothers of atopic babies. The polyamine levels were similar in colostrum from atopic and non-atopic mothers. However, putrescine and spermine levels were lower in mature milk from atopic mothers than non-atopic mothers. No relationship was found between milk putrescine and spermine levels and development of atopy in the children. In conclusion, low levels of human milk putrescine and spermine seem to be related to maternal atopy.

Chromatography, High Pressure Liquid↗
PubMed2001

Modified responses to PGE2 in polyamine biosynthesis by T lymphocytes of gastric- and conjunctiva basal cell-carcinoma patients.

The response to Prostaglandin (PG) E2 of T cells from gastric carcinoma (GC)- and conjunctiva-basal cell carcinoma (conjunctiva-BCC)-bearing patients has been studied in relation to polyamine metabolism. Polyamines are crucial co-factors in cell growth as well as differentiation and many works report that lymphocyte spermine (SP), spermidine (SPD) and putrescine (PUT) levels may be related to tumor proliferation. The present work aims to detect the basal and PGE2 induced concentrations of these polyamines and cAMP, ornithine decarboxylase (ODC), spermine N1-acetyltransferase (SAT) activities of T lymphocytes drawn from patients suffering from GC and conjunctiva-BCC since many carcinomas are characterized by high levels of PGE2. Data obtained from lymphocytes of neoplastic subjects were compared with those derived from PGE2-treated control lymphocytes. Results highlight a very significant increase of all the polyamine metabolites in PGE2-treated T cells from neoplastic patients in respect to the untreated and PGE2-treated control lymphocytes. Therefore, it is conceivable that the PGE2 content increase, often occurring during the epithelial tumour development, may contribute, through enhancement of polyamine metabolism, to tumor progression.

Acetyltransferases↗
PubMed1993

Polyamines are essential for cell transformation by pp60v-src: delineation of molecular events relevant for the transformed phenotype.

Ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis, becomes upregulated during cell proliferation and transformation. Here we show that intact ODC activity is needed for the acquisition of a transformed phenotype in rat 2R cells infected with a temperature-sensitive mutant of Rous sarcoma virus. Addition of the ODC inhibitor alpha-difluoromethyl ornithine (DFMO) to the cells (in polyamine-free medium) before shift to permissive temperature prevented the depolymerization of filamentous actin and morphological transformation. Polyamine supplementation restored the transforming potential of pp60v-src. DFMO did not interfere with the expression of pp60v-src or its in vitro tyrosine kinase activity. The tyrosine phosphorylation of most cellular proteins, including ras GAP, did not either display clear temperature- or DFMO-sensitive changes. A marked increase was, however, observed in the tyrosine phosphorylation of phosphatidylinositol 3-kinase and proteins of 33 and 36 kD upon the temperature shift, and these hyperphosphorylations were partially inhibited by DFMO. A DFMO-sensitive increase was also found in the total phosphorylation of calpactins I and II. The well-documented association of GAP with the phosphotyrosine-containing proteins p190 and p62 did not correlate with transformation, but a novel 42-kD tyrosine phosphorylated protein was complexed with GAP in a polyamine- and transformation-dependent manner. Further, tyrosine phosphorylated proteins of 130, 80/85, and 36 kD were found to coimmunoprecipitate with pp60v-src in a transformation-related manner. Altogether, this model offers a tool for sorting out the protein phosphorylations and associations critical for the transformed phenotype triggered by pp60v-src, and implicates a pivotal role for polyamines in cell transformation.

Actin Cytoskeleton↗
PubMed1995

The mechanism of inward rectification of potassium channels: "long-pore plugging" by cytoplasmic polyamines.

The mechanism of inward rectification was examined in cell-attached and inside-out membrane patches from Xenopus oocytes expressing the cloned strong inward rectifier HRK1. Little or no outward current was measured in cell-attached patches. Inward currents reach their maximal value in two steps: an instantaneous phase followed by a time-dependent "activation" phase, requiring at least two exponentials to fit the time-dependent phase. After an activating pulse, the quasi-steady state current-voltage (I-V) relationship could be fit with a single Boltzmann equation (apparent gating charge, Z = 2.0 +/- 0.1, n = 3). Strong rectification and time-dependent activation were initially maintained after patch excision into high [K+] (K-INT) solution containing 1 mM EDTA, but disappeared gradually, until only a partial, slow inactivation of outward current remained. Biochemical characterization (Lopatin, A. N., E. N. Makhina, and C. G. Nichols, 1994. Nature. 372:366-396.) suggests that the active factors are naturally occurring polyamines (putrescine, spermidine, and spermine). Each polyamine causes reversible, steeply voltage-dependent rectification of HRK1 channels. Both the blocking affinity and the voltage sensitivity increased as the charge on the polyamine increased. The sum two Boltzmann functions is required to fit the spermine and spermidine steady state block. Putrescine unblock, like Mg2+ unblock, is almost instantaneous, whereas the spermine and spermidine unblocks are time dependent. Spermine and spermidine unblocks (current activation) can each be fit with single exponential functions. Time constants of unblock change e-fold every 15.0 +/- 0.7 mV (n = 3) and 33.3 +/- 6.4 mV (n = 5) for spermine and spermidine, respectively, matching the voltage sensitivity of the two time constants required to fit the activation phase in cell-attached patches. It is concluded that inward rectification in intact cells can be entirely accounted for by channel block. Putrescine and Mg2+ ions can account for instantaneous rectification; spermine and spermidine provide a slower rectification corresponding to so-called intrinsic gating of inward rectifier K channels. The structure of spermine and spermidine leads us to suggest a specific model in which the pore of the inward rectifier channel is plugged by polyamines that enter deeply into the pore and bind at sites within the membrane field. We propose a model that takes into account the linear structure of the natural polyamines and electrostatic repulsion between two molecules inside the pore. Experimentally observed instantaneous and steady state rectification of HRK1 channels as well as the time-dependent behavior of HRK1 currents are then well fit with the same set of parameters for all tested voltages and concentrations of spermine and spermidine.

Animals↗
PubMed2006

Ring of negative charge in BK channels facilitates block by intracellular Mg2+ and polyamines through electrostatics.

Intracellular Mg2+ and natural polyamines block outward currents in BK channels in a highly voltage-dependent manner. Here we investigate the contribution of the ring of eight negatively charged residues (4 x E321/E324) at the entrance to the inner vestibule of BK channels to this block. Channels with or without (E321N/E324N) the ring of negative charge were expressed in oocytes and unitary currents were recorded from inside-out patches over a range of intracellular Mg2+ and polyamine concentrations. Removing the ring of charge greatly decreased the block, increasing K(B)(ap) (0 mV) for Mg2+ block from 48.3 +/- 3.0 to 143 +/- 8 mM, and for spermine block from 8.0 +/- 1.0 to 721 +/- 9 mM (150 mM symmetrical KCl). Polyamines with fewer amine groups blocked less: putrescine < spermidine < spermine. An equation that combined an empirical Hill function for block together with a Boltzmann function for the voltage dependence of K(B)(ap) described the voltage and concentration dependence of the block for channels with and without the ring of charge. The Hill coefficients for these descriptions were <1 for both Mg2+ and spermine block, and were unchanged by removing the ring of charge. When KCl(i) was increased from 150 mM to 3 M, the ring of charge no longer facilitated block, Mg2+ block was reduced, spermine block became negligible, and the Hill coefficients became approximately 1.0. BK channels in cell-attached oocyte patches displayed inward rectification, which was reduced for channels without the ring of charge. Taken together, these observations suggest that the ring of negative charge facilitates block through a preferential electrostatic attraction of Mg2+ and polyamine over K+. This preferential attraction of multivalent blockers over monovalent K+ would decrease the K+ available at the inner vestibule to carry outward current in the presence of Mg2+ or polyamines, while increasing the concentration of blocker available to enter and block the conduction pathway.

Algorithms↗
PubMed1993

Gender-related differences in the inhibitory effect on liver regeneration in alcohol-treated rats: study of polyamine metabolism.

We studied gender-related differences in the effect of a single dose of ethanol (EtOH) on liver regeneration following partial hepatectomy in male and female rats by determining polyamines and their related enzymes. When rats were orally treated with EtOH at 3 g/kg 1 hr before partial hepatectomy, liver ornithine decarboxylase (ODC) activity at 4 hr post-hepatectomy was found to be lower in EtOH-treated female than male rats (51% vs. 42%, P < 0.01). Although no EtOH effect was observed on spermidine acetyltransferase (SAT) activity, female rats showed significantly higher values than male rats. Among intra-hepatic polyamines, putrescine was strongly affected by EtOH and significantly reduced in both male and female rats, but the effect was more marked in female than in male rats (88% vs. 51%, P < 0.01). With respect to spermidine and spermine, male rats were unaffected by EtOH, whereas EtOH-treated female rats had lower levels. The gender-related differences became more distinct in terms of total polyamine; the decrease in total polyamine due to EtOH was observed in female rats only. These results suggested that there was a gender-related difference in the effect of EtOH on liver regeneration after partial hepatectomy, with the variations in polyamines probably affecting the subsequent process of liver regeneration.

Acetyltransferases↗
PubMed1997

Involvement of polyamines in selenomethionine induced apoptosis and mitotic alterations in human tumor cells.

The efficacy of dietary selenium supplementation is currently being evaluated in intervention trials. However, the biological mechanisms underlying the cancer chemopreventive effects of selenium supplementation have yet to be elucidated. Selenium metabolism and polyamine biosynthesis are linked in their common requirement for S-adenosylmethionine. Selenomethionine was the predominant form of selenium in the dietary supplement, therefore we evaluated the anti-tumorigenic effects of selenomethionine. We found that selenomethionine inhibited tumor growth (both in A549 lung and HT29 colon cancer cells) in a dose-dependent manner. At 24 and 72 h, polyamine content of A549 and HT29 cancer cell lines was decreased at doses that inhibited 50% of normal growth. Selenomethionine treatment induced apoptosis in both cancer cell lines. Exogenous spermine administration, which replenishes intracellular polyamine levels, prevented selenomethionine induced apoptosis. Selenomethionine administration to the cancer cell lines increased the number of cells in metaphase. This cell cycle effect appeared to be reversed with the co-administration of selenomethionine and spermine. These data suggested that at least part of the anti-carcinogenic effects of selenium supplementation might be due to a depletion in polyamine levels. This depletion of polyamines leads to an induction in apoptosis and perturbations in the cell cycle.

Antineoplastic Agents↗
PubMed1981

Intrahepatic polyamine levels during rat liver carcinogenesis induced by N-2-fluorenylacetamide.

During a period of 200 days, the chronological changes of polyamine levels (putrescine, spermidine and spermine) were observed in the liver of adult female Sprague Dawley rats submitted to hepatocarcinogenesis by N-2-fluorenylacetamide (FAA). Three groups of 70 rats each were used: (1) Control 1: normal diet; (2) Control 2: low protein and low riboflavin diet; and (3) EXPERIMENTAL: 0.06% FAA added to the diet. No significant differences were noted for tissue levels of the three polyamines when the two control groups were compared. In contrast, considerable variations of these molecules were observed as a function of time in the FAA treated group: (a) an early and constant rise was seen in putrescine, with 3 maxima at days 10, 60 and 150. This last peak was the highest: 25 +/- 6 nmol/g (8 times the value for the controls at this time), and coincided with the appearance of cancerous lesions. (b) While spermidine levels varied during the experiment, no significant differences were noted in comparison with the control groups. Mean levels (nmol/g) were: 535 +/- 108 Control 1; 552 +/- 95 Control 2; 633 +/- 160 FAA-treated group. (c) Spermine levels were significantly lowered, with 3 minima corresponding to the putrescine maxima. The lowest minima was observed on day 60: 114 +/- 67 nmol/g, i.e., 4 times lower than the controls. This work shows that polyamine metabolism is profoundly modified during chemical carcinogenesis, but the possible effect of polyamines on tumorigenesis itself cannot be assessed at this point since modifications of polyamine levels are probably also associated with phenomena of liver necrosis and compensatory tissue proliferation observed during the experiment.

2-Acetylaminofluorene↗
PubMed2001

Activation of caspase-3 activity and apoptosis in MDA-MB-468 cells by N(omega)-hydroxy-L-arginine, an inhibitor of arginase, is not solely dependent on reduction in intracellular polyamines.

We have shown previously that (NOHA) an intermediate in the nitric oxide (NO) synthetic pathway and an inhibitor of arginase significantly reduced intracellular polyamines, activated caspase-3 and induced apoptosis in the human breast cancer cell line MDA-MB-468. These actions of NOHA were abolished in the presence of exogenous L-ornithine suggesting that a reduction in the intracellular polyamine content might be responsible for the activation of caspase-3 and apoptotic actions of NOHA. In order to further explore this possibility, we used SAM-486A and alpha-difluoromethylornithine (DFMO), which are inhibitors of S-adenosylmethionine decarboxylase (SAMDC), and ornithine decarboxylase (ODC), respectively, either alone or in combination to reduce the intracellular polyamine levels. We then assessed whether a reduction in polyamine levels by these two compounds to a similar degree to that produced by NOHA activated caspase-3 which occurs prior to the onset of apoptosis. We observed that both SAM-486A and DFMO, either alone or in combination, inhibited cell proliferation, induced p21 and arrested cells in the G(0)-G(1) phase of the cell cycle but failed to activate caspase-3 as assessed by enzymatic assay of caspase-3, western blot analysis of the proteolytic cleavage of caspase-3 protein as well as TUNEL assay. Furthermore, pre-incubation of the cells with SAM-486A and DFMO for 4 days, either alone or in combination significantly inhibited the activation of caspase-3 and apoptosis by NOHA when compared with that observed with cells treated with NOHA alone. Our results, therefore, indicate that the activation of caspase-3 and apoptosis observed with NOHA cannot be solely explained by a reduction in intracellular polyamine levels and that other mechanisms need to be also considered.

Adenosylmethionine Decarboxylase↗
PubMed1985

Early stimulation of polyamine biosynthesis during promotion by phenobarbital of diethylnitrosamine-induced rat liver carcinogenesis. The effects of variations of the S-adenosyl-L-methionine cellular pool.

A decrease of S-adenosyl-L-methionine liver content was observed between the 14th and the 35th day after the start of 2-acetylaminofluorene feeding in diethylnitrosamine-initiated rats according to the 'resistant-hepatocyte' model of hepatocarcinogenesis. The decrease was enhanced by phenobarbital given to the animals after the end of 2-acetylaminofluorene feeding. These changes were associated with an increase in ornithine decarboxylase activity and the spermidine:spermine ratio. S-adenosyl-L-methionine administration to rats caused a great fall in the percentage of gamma-glutamyltranspeptidase-positive liver as well as in polyamine synthesis. An increase in ornithine decarboxylase activity, associated with a decrease in the liver S-adenosyl-L-methionine pool, also occurred in normal animals on the first day following a partial hepatectomy and was enhanced by phenobarbital. The association of 2-acetylaminofluorene feeding with partial hepatectomy resulted in a slower liver regeneration, while the decrease in S-adenosyl-L-methionine level and the increase in polyamine synthesis were observed over a longer period of time after partial hepatectomy. These changes were further prolonged in diethylnitrosamine-initiated rats in which gamma-glutamyltranspeptidase-positive foci developed. In these animals a high level of polyamine synthesis was still present when liver regeneration was complete. At this stage of the observation period the labeling index was very low in surrounding liver, but still high in the gamma-glutamyltranspeptidase-positive areas. Phenobarbital stimulated polyamine synthesis and cell growth and further prolonged the period of time during which a high ornithine decarboxylase activity and labeling index were present. These results indicate that the liver lipotrope content could be a rate-limiting factor for cell growth and liver neoplasia promotion and this could depend on the modulation of polyamine biosynthesis.

2-Acetylaminofluorene↗
PubMed2002

Are polyamines involved in olfaction? An EAG and biochemical study in Periplaneta americana antennae.

Polyamines have been implicated in modulation of numerous cell functions. The purpose of this study was to assess the role of polyamines in intracellular regulation of insect antenna. Analysis of study data showed two main findings. First, in vivo treatment with the polyamine synthesis inhibitor alpha-difluoromethyl-ornithine enhanced the sensitivity of male Periplaneta americana antenna to female pheromonal blend. Secondly, polyamine modulated phosphorylation of several antennary proteins including two found exclusively in antenna (30 and 48 kDa). In both of these exclusive antennary proteins, phosphorylation changed after stimulation with the pheromonal blend. These results suggest that polyamines play a regulatory role in detection of female pheromonal blend and that modulation of protein phosphorylation is one of the mechanisms involved in this regulation.

Animals↗
PubMed1989

Isoprenaline induced changes in ornithine decarboxylase activity and polyamine content in regions of the rat heart.

Isoprenaline stimulated increases in ornithine decarboxylase activity and polyamine content in cardiac tissues are implicated in macromolecular synthesis and cellular growth, but little is known about polyamine metabolism in functionally distinct regions of the heart. We therefore determined regional changes in ornithine decarboxylase activity and polyamine content in the right and left ventricles, septum, and the right and left atria of the rat following the administration of isoprenaline. An increase in ornithine decarboxylase specific activity and tissue polyamine content occurred in all cardiac regions, but the highest ornithine decarboxylase activity was found in the septum. Propranolol inhibited the isoprenaline stimulated ornithine decarboxylase activity in all the regions. Putrescine increased and peaked between 6 and 8 h in right and left ventricles and septum and declined to a control level by 12 h. Following a peak increase at 8 h, spermidine and spermine contents of both ventricles were maintained at peak levels, while those in the septum declined to control values by 12 h. There was no detectable putrescine in the right atria from the control experiments and in either atrium at 2 h following isoprenaline administration. Putrescine content peaked at 6 h in the right atrium and at 8 h in the left atrium and then declined. In both atria there was a peak increase in spermidine and spermine contents between 4 and 8 h. These results show that there is a regional variation in the accumulation of polyamines in the rat heart following isoprenaline administration.

Animals↗
PubMed1991

Polyamine metabolism in Pneumocystis carinii.

Alpha-difluoromethylornithine (DFMO) is being used to treat Pneumocystis carinii pneumonia despite a lack of in vitro evidence supporting its antipneumocystis activity. DFMO is a specific inhibitor of ornithine decarboxylase, the rate-limiting enzyme of polyamine biosynthesis. To investigate polyamine metabolism in P. carinii, extracts of the organism were analyzed for polyamine content and ornithine decarboxylase activity, and [3H]ornithine and [14C]arginine incorporation into polyamines during short-term culture was determined. P. carinii extracts contained putrescine and spermidine in a ratio of 0.17:1; traces of spermine were detected. Although ornithine decarboxylase activity was not detected, P. carinii incorporated ornithine and arginine into putrescine and spermidine but not into spermine, suggesting that the spermine detected derived from contaminating host cells. Uninfected rat lung incorporated ornithine minimally. Pentamidine, DFMO, and alpha-monofluoromethyldehydroornithine methyl ester inhibited ornithine incorporation by up to 86% at clinically achievable concentrations. These data provide a rationale for using polyamine synthesis antagonists in P. carinii pneumonia and a method for screening antipneumocystis drugs in vitro.

Animals↗
PubMed2006

Mammalian polyamine catabolism: a therapeutic target, a pathological problem, or both?

With the recent discovery of the polyamine catabolic enzyme spermine oxidase (SMO/PAOh1), the apparent complexity of the polyamine metabolic pathway has increased considerably. Alone or in combination with the two other known members of human polyamine catabolism, spermidine/spermine N(1)-acetyltransferase, and N(1)-acetylpolyamine oxidase (PAO), SMO/PAOh1 expression has the potential to alter polyamine homeostasis in response to normal cellular signals, drug treatment and environmental and/or cellular stressors. The activity of the oxidases producing toxic aldehydes and the reactive oxygen species (ROS) H(2)O(2), suggest a mechanism by which these oxidases can be exploited as an antineoplastic drug target. However, inappropriate activation of the pathways may also lead to pathological outcomes, including DNA damage that can lead to cellular transformation. The most recent data suggest that the two polyamine catabolic pathways exhibit distinct properties and understanding these properties should aid in their exploitation for therapeutic and/or chemopreventive strategies.

Acetyltransferases↗
PubMed1998

Dietary guar gum and pectin stimulate intestinal microbial polyamine synthesis in rats.

The effects of two highly fermentable dietary fibers (guar gum and pectin) on the type and concentrations of cecal polyamines as affected by the intestinal microflora were studied in groups of germ-free (n = 10/group) and conventional rats (n = 6/group). Both germ-free and conventional rats were randomly assigned to one of three treatments as follows: 1) fiber-free control diet, 2) control diet + 10% guar gum and 3) control diet + 10% pectin. In germ-free rats, guar gum and pectin had no effect on cecal polyamine concentrations. Putrescine was confirmed to be the major endogenous polyamine within the gut lumen. In cecal contents of conventional rats, both guar gum and pectin led to the appearance of cadaverine and to elevated putrescine concentrations in comparison with the fiber-free control diet (1.35 +/- 0.15 and 2.27 +/- 0.32, respectively, vs. 0.20 +/- 0.03 micromol/g dry weight, P < 0.05). The cecal cadaverine concentration was higher in pectin- than in guar-fed rats (8.20 +/- 0.89 vs. 1.92 +/- 0.27 micromol/g dry weight, P < 0.05). Counts of total bacteria, bacteroides, fusobacteria and enterobacteria were higher (P < 0.05) in rats fed guar gum and pectin. Bifidobacteria were found exclusively in guar-fed rats. In vitro studies on selected species representing the numerically dominant population groups of the human gut flora (bacteroides, fusobacteria, anaerobic cocci and bifidobacteria) were examined for their ability to synthesize intracellular polyamines. These experiments demonstrated the ability of bacteroides, fusobacteria and anaerobic cocci to synthesize high amounts of putrescine and spermidine. Calculations based on these results suggest that the intestinal microflora are a major source of polyamines in the contents of the large intestine.

Animals↗
PubMed2006

Inhibition of the ethylene response by 1-MCP in tomato suggests that polyamines are not involved in delaying ripening, but may moderate the rate of ripening or over-ripening.

Ethylene initiates the ripening and senescence of climacteric fruit, whereas polyamines have been considered as senescence inhibitors. Ethylene and polyamine biosynthetic pathways share S-adenosylmethionine as a common intermediate. The effects of 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception, on ethylene and polyamine metabolism and associated gene expression was investigated during ripening of the model climacteric fruit, tomato (Solanum lycopersicum L.), to determine whether its effect could be via polyamines as well as through a direct effect on ethylene. 1-MCP delayed ripening for 8 d compared with control fruit, similarly delaying ethylene production and the expression of 1-aminocyclopropane-1-carboxylic acid (ACC)-synthase and some ethylene receptor genes, but not that of ACC oxidase. The expression of ethylene receptor genes returned as ripening was reinitiated. Free putrescine contents remained low while ripening was inhibited by 1-MCP, but increased when the fruit started to ripen; bound putrescine contents were lower. The activity of the putrescine biosynthetic enzyme, arginine decarboxylase, was higher in 1-MCP-treated fruit. Activity of S-adenosylmethionine-decarboxylase peaked at the same time as putrescine levels in control and treated fruit. Gene expression for arginine decarboxylase peaked early in non-treated fruit and coincident with the delayed peak in putrescine in treated fruit. A coincident peak in the gene expression for arginase, S-adenosylmethionine-decarboxylase, and spermidine and spermine synthases was also seen in treated fruit. No effect of treatment on ornithine decarboxylase activity was detected. Polyamines are thus not directly associated with a delay in tomato fruit ripening, but may prolong the fully-ripe stage before the fruit tissues undergo senescence.

Adenosylmethionine Decarboxylase↗
PubMed1982

Polyamine-induced hydrolysis of apurinic sites in DNA and nucleosomes.

The ability of different polyamines to catalyze hydrolysis of phosphodiester linkages in apurinic and apyrimidinic (AP) sites has been investigated in supercoiled, relaxed and denatured DNA, and also in core and chromatosome particles. The rate constants for the hydrolysis in the DNAs have been determined. In general the order of effectiveness of the polyamines were: spermine greater than spermidine greater than putrescine greater than cadaverine. A 9 fold difference in rate constants was found between spermine and cadaverine. No difference in the rate of hydrolysis was seen between AP-sites in supercoiled and relaxed DNAs, whereas the rate for the single-stranded DNA and DNA in core and chromatosome particles was only half of that in the double-stranded DNA. All AP-sites in both free DNA and DNA-histone particles were hydrolyzed in the presence of polyamines. For all polyamines, with the exception of spermine, increasing concentration of both Mg++ and salts such as KCl both led to a large decrease in the rate of polyamine-induced hydrolysis of AP-sites. The rate of hydrolysis increased markedly with increasing pH in the pH range pH 6 - pH 11.

Animals↗
PubMed1997

Effects of natural and synthetic polyamines on the conformation of an oligodeoxyribonucleotide with the estrogen response element.

We studied the effects of natural and synthetic polyamines on the conformation of an oligodeoxyribonucleotide (ODN1) harboring the estrogen response element (ERE) by circular dichroism (CD) spectroscopy and polyacrylamide gel electrophoresis. Putrescine and spermidine had no marked effect on the CD spectrum of ODN1. In contrast, spermine provoked and stabilized two characteristic changes in the CD spectrum. The first change was indicated by an increase in the intensity of the CD band at 280 nm at 0.5 mM spermine in Tris-HCl buffer containing 50 mM NaCl. This change appears to be related to changes in base tilt and conformational alterations similar to A-DNA. At 1-2 mM spermine, the CD spectrum was characterized by a loss of positive bands at 220 and 270 nm. This change might have contributions from polyamine-induced condensation/aggregation of DNA. Spectral measurements were also conducted in Tris-HCl buffer containing 150 mM NaCl to minimize contributions from condensation and aggregation of ODN1. Under these conditions, CD spectral changes were retained by (ODN1), although the magnitude of the change was diminished. In contrast, a control oligdeoxyribonucleotide (ODN2) having similar base composition did not show any significant change in the CD spectrum in the presence of 150 mM NaCl and 2 mM spermine. The changes in the CD spectrum of ODN1 were highly sensitive to polyamine structure, as evidenced by experiments using spermine analogs with altered number of -CH2- groups separating the amino and imino groups. Electrophoretic mobility shift analysis further showed ODN1 stabilization by spermine and its analogs. These data demonstrate the ability of an ODN containing ERE to undergo conformational transitions in the presence of polyamines and suggest a possible mechanism for polyamine-mediated alterations in the interaction of estrogen receptor with ERE.

Base Sequence↗