Polyamine binding

About: Polyamine binding is a research topic. Over the lifetime, 188 publications have been published within this topic receiving 9206 citations.

Endogenous protein-bound polyamines: correlation with regions of cell division in tobacco leaves, internodes and ovaries

Abstract: We have previously reported the binding of exogenous labeled spermidine to a developmentally regulated 18 kD protein in thin-layer tobacco tissue cultures [1] and to protein larger than 45 kD in mesophyll protoplasts of oat [16]. To assess the possible biological importance of this phenomenon we have now studied the binding of endogenous polyamines to proteins in three developmental systems, the internodes, leaves and ovaries of tobacco (Nicotiana tabacum L cv. Wisconsin-38), each containing regions of cell division, cell enlargement and quiescence. Endogenous polyamine binding proteins were more abundant in actively dividing regions of apical internodes, young leaves and ovaries than in mature basal internodes, fully expanded leaves and ovaries at the green fruit stage, respectively. Spermidine binding was highest in young ovaries while putrescine binding was highest in young leaves. The results suggest a relation between polyamine binding proteins and mitotic activity.

Quantitation of cation binding to wheat germ ribosomes: Influences on submit association equilibria and ribosome activity

Abstract: The binding of Mg2+, spermine, and spermidine to wheat germ ribosomes was quantitated following equilibrium dialysis. The Mg2+ binding data demonstrate that Mg2+ and K+ compete for binding to the ribosomes. Mg2+ binding saturates at approximately 0.56 positive charges per phosphate (+/P). The Mg2+, spermine and spermidine binding data indicate that either polyamine replaces Mg2+ upon binding to the ribosomes. Mg2+ and polyamine binding combined saturates at approximately 0.29 +/P under the conditions reported. When a critical number of Mg2+ ions are replaced by either polyamine, the activity of the ribosomes falls dramatically. Ribosomal subunit association increases with the degree of phosphate charge neutralization due to the binding of Mg2+. Total charge neutralization during subunit association by Mg2+ and polyamine binding combined, is much less than that achieved by Mg2+ alone.

Histamine Potentiates N-Methyl-d-aspartate Receptors by Interacting with an Allosteric Site Distinct from the Polyamine Binding Site

Abstract: Histamine potentiates activation of native and recombinant N-methyl-d-aspartate receptors (NMDARs), but its mechanisms of action and physiological functions in the brain remain controversial. Using four different models, we have further investigated the histamine-induced potentiation of various NMDAR-mediated responses. In single cultured hippocampal neurons, histamine potentiated NMDA currents. It also potentiated the NMDA-induced increase in intracellular calcium in the absence, as well as with saturating concentrations, of exogenous d-serine, indicating both glycine-dependent and glycine-independent components of its effect. In rat hippocampal synaptosomes, histamine strongly potentiated NMDA-induced [(3)H]noradrenaline release. The profile of this response contained several signatures of the histamine-mediated effect at neuronal or recombinant NMDARs. It was NR2B-selective, being sensitive to micromolar concentrations of ifenprodil. It was reproduced by tele-methylhistamine, the metabolite of histamine in brain, and it was antagonized by impromidine, an antagonist/inverse agonist of histamine on NMDA currents. Up to now, histamine was generally considered to interact with the polyamine site of the NMDAR. However, spermine did not enhance NMDA-induced [(3)H]noradrenaline release from synaptosomes, and the potentiation of the same response by tele-methylhistamine was not antagonized by the polyamine antagonist arcaine. In hippocampal membranes, like spermine, tele-methylhistamine enhanced [(3)H]dl-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic acid (CGP39653) binding to the glutamate site. In contrast, spermine increased nonequilibrium [(3)H]5H-dibenzo[a,d]cyclohepten-5,10-imine (dizocilpine maleate; MK-801) binding, and suppressed [(3)H]ifenprodil binding, whereas histamine and tele-methylhistamine had no effect. In conclusion, the histamine-induced potentiation of NMDARs occurs in the brain under normal conditions. Histamine does not bind to the polyamine site, but to a distinct entity, the so-called histamine site of the NMDAR.