Eukaryotes polyamines

Spermine is one of the most common natural polyamines in eukaryotes with the following structure NH2(CH2)3NH(CH2)4NH(CH2)3NH2. 

Pegg AE (1986) Recent advances in the biochemistry of polyamines in eukaryotes. Biochem J 234 249-262... 

Tachezy J, Sanchez LB, Muller M (2001) Mitochondrial type iron-sulfur cluster assembly in the amitochondriate eukaryotes Trichomonas vaginalis and Giardia intestinalis, as indicated by the phylogeny of IscS. Mol Biol Evol 18 1919-1928 Tadolini (1988) Polyamine inhibition of lipoperoxidation the influence of polyamines on iron oxidation in the presence of compounds mimicking phospholipid polar heads. Biochem J 249 33-36... 

Genomics can also reveal unexpected biochemical potential. For example, the genome sequencing of the diatom Thalassiosira pseudonana revealed genes encoding aU the enzymes in a complete urea cycle, which is unprecedented in other eukaryotic photoautotrophs. It is hypothesized that intermediates from the urea cycle may be used to synthesize polyamines including those required for frustule formation (Armbrust et ai, 2004). 

The first key step in the biosynthesis of tropane alkaloids is the formation of the intermediate putrescine. Polyamines and, therefore putrescine, are found in plant cells and are implicated in growth, root, fruit and flower development, and in different stress phenomena. It is well known that plants synthesize polyamines from ornithine and arginine, unlike other eukaryotes like mammals, which only synthesize polyamines from ornithine. In plants putrescine is synthesized directly from ornithine, a reaction catalysed by ornithine decarboxylase (ODC, EC 4.1.1.17) and indirectly from arginine via agmatine catalysed by arginine decarboxylase (ADC, EC 4.1.1.19), Fig. (1). In Arabidopsis, it is known that the adc gene is required for the production of polyamines that are essential for normal seed development [103]. 

Another source of post-mortem GHB production is putrescine (1,4-butanediamine), a biogenic polyamine initially detected in decaying animal tissues, but now known to be present in all cells, both eukaryotic and prokaryotic, where it is important for cell... 

What are the major protein components of prokaryotic and eukaryotic chromosome What are their functions What are the polyamines and what role do they play in DNA structure QUESTION 1 7.S... 

In the prokaryotic chromosome there is a protein core to which the circular DNA molecule is attached. In addition, HU protein binds to the DNA and facilitates its bending and super-coiling. In eukaryotic chromosomes, DNA forms complexes with the histones to form nucleosomes. The polyamines are polycationic molecules that bind to negatively charged DNA so the latter molecule can overcome charge repulsions between adjacent coils during the compression process. 

The elimination of a CO2 molecule from the substrate catalyzed by decarboxylases requires the stabilization of a carbanionic intermediate, a task often performed by enzymatic cofactors. Indeed, decarboxylation reactions on ct-amino acids are catalyzed mainly by PLP-dependent enzymes, with a small fraction of reactions catalyzed by enzymes that use a pyruvoyl cofactor." PLP-dependent decarboxylases are largely widespread among both eukaryotes and prokaryotes where they participate in the biosynthesis of biological amines (e.g., dopamine, histamine, and serotonine) and polyamines. In addition, in prokaryotes, inducible PLP-dependent decarboxylases take part in the regulation of intracellular pH." ... 

Polyamines are low-molecular-weight molecules which are found in both prokaryotes and eukaryotes, and which fulfil essential needs for growth, division and differentiation. The most common poly amines are putrescine (1,4-diaminobutane tetramethylene-diamine), spermidine (N-(3-aminopropyl)-l,4-butane diamine) and spermine (N,N -bis(3-aminopropyl)-1,4-butane diamine). Cadaverine (1,5-diaminopentane) is also found in some micro-organisms (1,2). Most prokaryotes do not contain spermine but all cells contain putrescine and spermidine, in most cases in millimolar concentrations. 

AdoMet decarboxylase is the second key enzyme in polyamine biosynthesis. In mammalian cells it is activated by putrescine and is also characterized by the presence of a PEST sequence and a short half-life (13). Trypanosome AdoMet decarboxylase, like ODC, has a long (>6h) half-life as shown by in vitro incubation studies with cycloheximide using procyclic and bloodstream trypomastigotes (Bacchi, unpublished results). The crude enzyme is only 50% stimulated by 1 mM putrescine (22) but in the partly purified state it is stimulated 8-fold by 2mM putrescine (23). Trypanosome AdoMet decarboxylase, like other eukaryotic counterparts, contains a covalently... 

AdoMet is a critical branch point metabolite. In its decarboxylated form, it serves as aminopropyl group donor in polyamine synthesis as AdoMet it is the methyl group donor for most transmethylation reactions (Fig. 7.1). In eukaryotic cells AdoMet decarboxylase is activated by putrescine and is the rate-limiting step of polyamine biosynthesis. Since production of dc-AdoMet is irreversible (13) regulation of AdoMet decarboxylase by putrescine determines the overall rate of polyamine synthesis. 

Most pyrrolizidine alkaloids are esters of basic alcohols known as necine bases. The most frequently studied pyrrolizidine alkaloids are formed from the polyamines, putrescine and spermidine, and possess one of three common necine bases retronecine, heliotridine, and otonecine. Putrescine is utilized exclusively as a substrate in secondary metabolism, whereas spermidine is a universal cell-growth factor involved in many physiological processes in eukaryotes. Spermidine biosynthesis begins with the decarboxylation of SAM by SAM decarboxylase 165). The aminopropyl group is then transferred from decarboxylated SAM to putrescine by spermidine synthase to form spermidine (Scheme 5). Putrescine can be produced from ornithine by ODC. However, putrescine is derived from the arginine-agmatine pathway in pyrrolizidine alkaloid-producing plants due to the absence of ODC activity 166). 

In addition to the classic bidentate chelate ligand ethylene diamine, a tremendous variety of linear polyamine ligands such as spermine, spermidine, putrescine, and cadaverine are known, many of which have biochemical roles as their somewhat evocative names suggest (Figure 12). Both spermidine and spermine, which is formed from it, are involved in cellular metabolism in eukaryotic cells. Spermine is an essential growth factor in some bacteria and exists as a polycation at physiological pH because the propylene and... 

Gambacorta, Polyamine distribution in eukaryotes occurrence of sym-nor-spermidine and sym-nor-spermine in arthropods,... 

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