Spermine Complexes Research Articles

Mechanisms of Efficient Desalination by a Two-Dimensional Porous Nanosheet Prepared via Bottom-Up Assembly of Cucurbit[6]urils.

Many researchers have examined the desalination performance of various kinds of two-dimensional (2D) porous nanosheets prepared by top-down approaches such as forming pores on the plain based on molecular dynamics (MD) simulations. In contrast, it is rare to find MD simulations addressing the desalination performance of a 2D porous nanosheet prepared by bottom-up approaches. We investigated the desalination performance of a 2D porous nanosheet prepared by the assembly of cucurbit[6]uril (CB[6]) via MD simulation. The model 2D CB[6] nanosheet features CB[6] with the carbonyl-fringed portals of 3.9 Å and the interstitial space filled with hydrophobic linkers and dangling side chains. Our MD simulation demonstrated that the 2D porous CB[6] nanosheet possesses a 70 to 140 times higher water permeance than commercial reverse osmosis membranes while effectively preventing salt passage. The extremely high water permeance and perfect salt rejection stem from not only CB[6]’s nature (hydrophilicity, negative charge, and the right dimension for size exclusion) but also the hydrophobic and tightly filled interstitial space. We also double-checked that the extremely high water permeance was attributable to only CB[6]’s nature, not water leakage, by contrasting it with a 2D nanosheet comprising CB[6]-spermine complexes. Lastly, this paper provides a discussion on a better cucurbituril homologue to prepare a next-generation desalination membrane possessing great potential to such an extent to surpass the 2D porous CB[6] nanosheet based on quantum mechanics calculations.

Spermine as a possible endogenous allosteric activator of carboxypeptidase A: multispectroscopic and molecular simulation studies

Carboxypeptidase A (EC.3.4.17.1) is a zinc-containing proteolytic enzyme that removes the C-terminal amino acid from a peptide chain with the free carboxylate-terminal. In this study, the effect of spermine interaction on the structure and thermal stability of Carboxypeptidase A was investigated by ultraviolet − visible spectroscopy, fluorescence spectroscopy, circular dichroism, Kinetic measurement, molecular docking and simulation studies have also been followed at the pH of 7.5. The transition temperature of Carboxypeptidase A, as a criterion of protein thermal stability, in the presence of spermine was enhanced by increasing the concentration of spermine. The results of fluorescence intensity changes, at two temperatures of 308 and 318 K, also suggested that spermine had a great ability to quench the fluorescence of Carboxypeptidase A through the static quenching procedure. The thermodynamic parameters changes, including standard Gibbs free-energy, entropy and enthalpy, showed that the binding of spermine to Carboxypeptidase A was spontaneous and the hydrogen bonding and van der Waals interactions played a major role in stabilizing the Carboxypeptidase A–spermine complex. The changes in the content of the α-helix and the β-sheet of the Carboxypeptidase A with binding to spermine were shown by the CD spectra method. Further, kinetic studies revealed that by increasing concentration of spermine, the activity of Carboxypeptidase A was enhanced. Also, the docking study revealed that the hydrogen bonding and van der Waals interactions played a major role in stabilizing the Carboxypeptidase A–spermine complex. As a result, spermine could be considered as an activator and a stabilizer for Carboxypeptidase A.Communicated by Ramaswamy H. Sarma

Interactions of a water-soluble calix[4]arene with spermine: solution and solid-state characterisation

The octaanionic 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)-calix[4]arene (cone conformation) (C4TsTc) was investigated as a sensor for the biogenic tetracationic polyamine, spermine .(H4Spe4+). Fluorescence titration experiments of the water-soluble calixarene with spermine showed the formation of the 2:1 and 1:1 calixarene:spermine complexes in solution. The single crystal X-ray diffraction analysis of [(NaC4TsTc)4·(H4Spe)7] confirmed the formation of 2:1 and 1:1 calixarene:spermine species and showed that the water-soluble calixarene binds the spermine either by partially hosting it in the inner cavity or through the carboxylate groups on the lower rim. In order to investigate the effect of multivalent systems, supramolecular assemblies of octaanionic calixarene molecules templated by meso-tetrakis(4-N-methylpyridyl)porphyrin (H2T4) in different stoichiometric porphyrin:calixarene ratios (1:4 and 3:4) were also tested for spermine binding in solution. Fluorescence titration experiments with the 1:4 and 3:4 H2T4:C4TsTc supramolecular complexes showed that the multivalent assemblies are more sensitive to the presence of spermine than the calixarene alone.

Complexation of Aliphatic Ammonium Ions with a Water‐Soluble Cucurbit[6]uril Derivative in Pure Water: Isothermal Calorimetric, NMR, and X‐ray Crystallographic Study

Complexation of a water-soluble cucurbituril (CB) derivative, cyclohexanocucurbit[6]uril (CB*[6]), the cavity dimensions of which are essentially the same as those of CB[6], with various organic mono- and diammonium ions has been studied by isothermal titration calorimetry and 1H NMR spectroscopy. The binding affinity of CB*[6] with the guest molecules in water is 3-5 and 2-3 orders of magnitude higher than those of CB[6] in 50 % formic acid and in 0.05 M NaCl solution, respectively, which is mainly due to the larger enthalpic gains upon complex formation in the absence of interfering ions, such as protons and Na+. In particular, the binding constant (K) of spermine to CB*[6] was measured to be 3.4 x 10(12) M(-1), which is the highest binding constant ever reported for CB[6] or its derivatives. We also obtained the X-ray crystal structures of alpha,omega-alkanediammonium ions (C(n)DA2+, n=4-8) and spermine complexes with CB[6], in which the aliphatic chains of the guest molecules take an extended or partially bent conformation inside the CB[6] cavity, depending on the chain length. The hexamethylene chain of C6DA2+ takes a twisted conformation, which not only allows strong ion-dipole interactions between the ammonium groups and the carbonyl groups at the portals, but also increases hydrophobic interactions between the alkyl part of the guest and the inner wall of the host, which results in the largest enthalpic gain among alpha,omega-alkanediammonium ions. The thermodynamic parameters associated with the complexation are discussed in relation to the binding modes and conformations of the aliphatic chain of the guest molecules inside the host, which were investigated by 1H NMR spectroscopy and X-ray crystallography.

Interactions of a Tetraanionic Porphyrin with DNA: from a Z-DNA Sensor to a Versatile Supramolecular Device

The anionic nickel(II) porphyrin NiTPPS is able to selectively sense the spermine induced left-handed Z-form of DNA while it is completely silent in the presence of right-handed B-DNA. Interactions between the DNA and the porphyrin can be easily modulated by pH and temperature. The resulting Z-DNA-porphyrin-spermine complex behaves as a supramolecular reversible information storage system and as a reversible AND logic gate.

Controlling the Biological Effects of Spermine Using a Synthetic Receptor

Polyamines play an important role in biology, yet their exact function in many processes is poorly understood. Artificial host molecules capable of sequestering polyamines could be useful tools for studying their cellular function. However, designing synthetic receptors with affinities sufficient to compete with biological polyamine receptors remains a huge challenge. Binding affinities of synthetic hosts are typically separated by a gap of several orders of magnitude from those of biomolecules. We now report that a dynamic combinatorial selection approach can deliver a synthetic receptor that bridges this gap. The selected receptor binds spermine with a dissociation constant of 22 nM, sufficient to remove it from its natural host DNA and reverse some of the biological effects of spermine on the nucleic acid. In low concentrations, spermine induces the formation of left-handed DNA, but upon addition of our receptor, the DNA reverts back to its right-handed form. NMR studies and computer simulations suggest that the spermine complex has the form of a pseudo-rotaxane. The spermine receptor is a promising lead for the development of therapeutics or molecular probes for elucidating spermine's role in cell biology.

Synthesis of Cucurbituril-spermine-[2]rotaxanes of the Amide-type

[2]Rotaxanes with the macrocyclic ligand cucurbituril were prepared in yields between 10 and 90% from the reaction of the spermine complex with cucurbituril and different carboxylic acid chlorides in a two phase Schotten-Baumann reaction. This reaction type offers the possibility to synthesize a lot of different [2]rotaxanes. They are characterised by elemental analysis, 1H-NMR spectroscopy and mass spectrometry.

Kinetic Analysis of Spermine Binding to NRD Convertase

N-arginine dibasic convertase cleaves polypeptides between paired basic residues containing the sequence Arg-Arg or Arg-Lys. The enzyme contains a large anionic domain, which in the rat enzyme consists of 57 acidic residues out of a stretch of 76 amino acids. Polyamines modulate the activity of the enzyme presumably by binding at the anionic domain (Csuhaiet al.(1995)Biochemistry34, 12411–12419). In this study a kinetic analysis of the effect of salts and amines, particularly the polyamine spermine, on the rat enzyme was studied. Simple salts were inhibitory with no apparent specificity for the anion or cation. Inhibition resulted in an increasedKmand a decreasedVmax. Evidence that amines bind to an anionic domain was obtained by the finding thatN,N-bis [2-hydroxyethyl]-2-aminoethanesulfonic acid, which is structurally related to the inhibitory amine triethanolamine, is noninhibitory. Inhibition exhibited a complex dependence on spermine concentration. The data fit a model in which enzyme–spermine and enzyme–(spermine)2complexes are formed. A pH-independentKd(∼0.1 μM) was obtained for enzyme–spermine formation, while enzyme–(spermine)2formation was dependent on pH;Kdat pH 6.5 = 1 μM and aKdat pH 8 = ∼16 μM. Direct binding of spermine was demonstrated by the ability of spermine to increase the thermal stability of the enzyme. The concentration dependence for the spermine-induced increase in thermal stability fits a model in which formation of the enzyme–spermine complex is sufficient to account for the observed changes.

Binding of polyanions by biogenic amines. III . Formation and stability of protonated spermidine and spermine complexes with carboxylic ligands

The formation and stability of protonated spermidine and spermine–carboxylic ligand complexes (seven systems) were studied potentiometrically (H +-glass electrode). ALH r species are formed (A=spermidine, spermine, L z− =acetate, malonate, 1,2,3-propanetricarboxylate, 1,2,3,4-butanetetracarboxylate; r=1... m+ n−1, where m and n are the maximum degree of protonation of the amine and of the carboxylic ligand, respectively), and their stability is a function of charges involved in the formation reaction. For the equilibrium H i A i+ +H j L ( j− z) =ALH i+ j ( i+ j− z) the linear relationship log K ij =0.46 ζ (ζ=∣ i( z− j)∣) was found. By means of this simple equation a mean free energy value can be obtained per salt bridge ( n), namely −Δ G°=5.25±0.15 kJ mol −1 n −1. Species formed by the highest charged ligands are quite stable ( K>10 3 mol −1 dm 3) and potentially play an important role in the speciation of biofluids, as shown by speciation diagrams and simulated experiments.

Formation of a Complex Containing ATP, Mg2+, and Spermine: STRUCTURAL EVIDENCE AND BIOLOGICAL SIGNIFICANCE

The conformation of ATP in the presence of Mg2+ and/or spermine was studied by 31P and 1H NMR, to clarify how polyamines interact with ATP. Spermine predominantly interacted with the beta- and gamma-phosphates of ATP in the presence of Mg2+. A conformational change of the beta- and gamma-phosphate of ATP with spermine could not be observed in the absence of Mg2+ by 31P NMR. It was found by 1H NMR that the conformation of adenosine moiety of ATP was not influenced significantly by spermine. The binding of Mg2+ to ATP was slightly inhibited by spermine and vice versa. The results indicate that the binding sites of Mg2+ and spermine on ATP only partially overlap. The PotA protein, an ATP-dependent enzyme, was used as a model system to study the biological role of the ATP-Mg2+-spermine complex. The ATPase activity of PotA was greatly enhanced by spermine. Double reciprocal plots at several concentrations of spermine as an activator indicate that spermine interacts with ATP, but not with PotA. The activity of protein kinase A was also stimulated about 2-fold by spermine. The results suggest that a ternary complex of ATP-Mg2+-spermine may play an important role in some ATP-dependent reactions in vivo and in the physiological effects of endogenous polyamines.

Thermodynamic parameters for the binding of ATP by protonated open-chain polyamines

The thermodynamic parameters of formation of ATP–protonated polyamine (ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, diethylenetriamine, spermidine, triethylenetetramine, spermine, tetraethylenepentamine and pentaethylenehexamine) complexes at 25 °C have been studied by potentiometry (H+-glass electrode and direct calorimetry). The formation constants of species for two, as yet untested, systems are also included. The thermodynamic parameters were obtained for all the systems studied from log K and ΔH0 values. It was found that ATP-protonated amine complexes are stabilized entropically. Empirical charge–stability relationships are shown

High-Yield Preparation of Oligomeric C-Type DNA Toroids and Their Characterization by Cryoelectron Microscopy

The quantitative and reversible compaction of open circular plasmid DNA (7676 bp) into toroids containing one to 19 molecules by sequential treatment with spermine and an excess of uranyl acetate is reported. The toroidal DNA structure was proven by cryoelectron microscopy. Linearized and supercoiled variants of the DNA also gave toroids under these conditions, but yields were significantly lower. In the presence of spermine alone no toroids were found. Open circular plasmid B-DNA helix was converted into the C-type helical form upon compaction as was shown by CD spectroscopy (negative peak at 255 nm) and electron microscopy (1.8-nm interduplex distance instead of 2.9 nm). Addition of uranyl salt to the DNA−spermine complexes resulted in the formation of netlike assemblies which further compacted to give toroids. A model containing a hexagonal arrangement of DNA strands with extensive strand crossings is proposed. Curvature and thus toroid formation is thought to be induced by the hydrophobic DNA coating ...

Multiple DNA binding modes of anthracene-9-carbonyl- N1-spermine

The poly(dAdT) 2 complex of anthracene-9-carbonyl- N 1-spermine, a spermine derivative terminally substituted with an anthracene moiety, has been studied using fluorescence, linear dichroism, circular dichroism, normal absorption spectroscopy (as a function of temperature) and computer modelling. For comparison, some data are also provided for the same ligand with poly(dGdC) 2 and calf thymus DNA. Following detailed fluorescence and CD spectroscopic studies, we propose that anthracene-9-carbonyl- N 1-spermine intercalates in at least two different binding orientations with poly(dAdT) 2. Based on computer simulation data, we deduce that the ligand can intercalate from both the minor groove and the major groove. In contrast, intercalation with poly(dGdC) 2 probably occurs only from the major groove. At high ligand concentrations, the CD spectra suggest anthracene-anthracene interactions, whilst the LD data point towards a groove-bound anthracene. Again from computer simulations, we propose binding modes consistent with these observations. Other data from the LD spectra suggest a sequential nature to the binding of the ligand to calf thymus DNA, with GC-rich sites being occupied first. At low ligand concentrations, anthracene-9-carbonyl- N 1-spermine is able to stabilize poly(dAdT) 2 against thermal decomposition, but not as effectively as spermine. The reverse is found to be true with calf thymus DNA. Both the anthracene-9-carbonyl- N 1-spermine and spermine complexes of poly(dAdT) 2 show pre-melt transitions in their melting curves. The anthracene-9-carbonyl- N 1-spermine complex with poly(dAdT) 2 also shows a post-melt transition.

Crystal and molecular structure of aqua spermine copper (II) sulphate trihydrate studied by X-ray and IR spectroscopy

The title compound [(C10H26N4)·Cu+2·H2O]·SO 4 −2 ·3H2O[A] has been studied by X-ray diffraction and IR spectroscopy. It crystalized in monoclinic system, in space group P 2l/c, with cell dimensions ofa=8.128(2),b=15.472(2),c=15.350(2) A, β=102.66(2)°. The copper atom is five coordinated with four nitrogen atoms and one axial water molecule forming tricyclic chelated spermine complex. The chelated complex consists of two six-membered and one sevenmembered rings. The seven membered ring is disordered. The amine groups from spermine molecule are hydrogen bonded to the sulphate anion and the water molecule. All water molecules form an infinitive hydrogen bonding network utilizing sulphate anions as bridges. The IR analysis before and after dehydration of [A] agree with the X-ray results.

Crystal structure of the highly distorted chimeric decamer r(C)d(CGGCGCCG)r(G).spermine complex--spermine binding to phosphate only and minor groove tertiary base-pairing.

The crystal structure of the self-complementary chimeric decamer duplex r(C)d(CGGCGCCG)r(G), with RNA base pairs at both termini, has been solved at 1.9 A resolution by the molecular replacement method and refined to an R value of 0.145 for 2,314 reflections. The C3'-endo sugar puckers of the terminal riboses apparently drive the entire chimeric duplex into an A-DNA conformation, in contrast to the B-DNA conformation adopted by the all-deoxy decamer of the same sequence. Five symmetry related duplexes encapsulate a spermine molecule which interacts with ten phosphate groups, both directly and through water molecules to form multiple ionic and hydrogen bonding interactions. The spermine interaction severely bends the duplexes by 31 degrees into the major groove at the fourth base pair G(4).C(17), jolts it and slides the 'base plate' into the minor groove. This base pair, together with the adjacent base pair in the top half and the corresponding pseudo two-fold related base pairs in the bottom half, form four minor groove base-paired multiples with the terminal base pairs of two neighboring duplexes.

Ternary interactions of spermine with DNA: 4′-epiadriamycin and other DNA: anthracycline complexes

The recently developed anthracycline 4'-epiadriamycin, an anti-cancer drug with improved activity, differs from adriamycin by inversion of the stereochemistry at the 4'-position. We have cocrystallized 4'-epiadriamycin with the DNA hexamer d(CGATCG) and solved the structure to 1.5 A resolution using x-ray crystallography. One drug molecule binds at each d(CG) step of the hexamer duplex. The anthracycline sugar binds in the minor groove. A feature of this complex which distinguishes it from the earlier DNA:adriamycin complex is a direct hydrogen bond from the 4'-hydroxyl group of the anthracycline sugar to the adenine N3 on the floor of the DNA minor groove. This hydrogen bond results directly from inversion of the stereochemistry at the 4'-position. Spermine molecules bind in the major groove of this complex. In anthracycline complexes with d(CGATCG) a spermine molecule binds to a continuous hydrophobic zone formed by the 5-methyl and C6 of a thymidine, C5 and C6 of a cytidine and the chromophore of the anthracycline. This report discusses three anthracycline complexes with d(CGATCG) in which the spermine molecules have different conformations yet form extensive van der Waals contacts with the same hydrophobic zone. Our results suggest that these hydrophobic interactions of spermine are DNA sequence specific and provide insight into the question of whether DNA:spermine complexes are delocalized and dynamic or site-specific and static.

Partial purification and characterization of a cell specific G 1-inhibitor (chalone) from JB-1 ascites tumors

Cell-specific G 1 -inhibitory (chalone) activity has been extracted from old JB- 1 ascites tumors and purified by means of G- 15 Sephadex chromatography. Four peaks of activity were obtained, the amount of activity in each peak varying from batch to batch. The first eluting activity peak probably represents chalone activity present in an aggregated form. The latest eluting activity peak was totally unspecific and could be attributed to the presence of high amounts of salts. The two intermediary peaks of activity were investigated in more detail. It is shown that the first eluting activity peak of these two is due to the polyamine spermine complexed to a carrier. Although the spermine complex exhibits a certain degree of cell-specific inhibitory activity in vitro, it is totally inactive in vivo. The second eluting activity peak containing the main part of cell-specific G-inhibitory activity has been characterized as a small molecular weight ( M r 300–600), ampholytic, hydrophobic, slightly acidic, and thiol-containing peptide active both in vitro and in vivo.

Interaction of spermine with different forms of DNA. A conformational study.

AbstractThe energy of interaction of a spermine molecule with the A‐ and B‐forms of DNA has been calculated, assuming that the molecule of spermine is fixed in the narrow groove of the DNA helix with the formation of hydrogen bonds between the amino groups of spermine and the phosphate groups of DNA. The atom–atom potentials method was used. Optimal structures for the A‐DNA–spermine and B‐DNA–spermine complexes are suggested. It is shown that, in agreement with the experimental data, the interaction of the spermine molecule with the A‐DNA is energetically more favorable than that with the B‐DNA. Two main factors are responsible for this: (1) the distance between neighboring phosphates of the chain in A‐DNA (which is about 1 Å less than that in B‐DNA) corresponds better to the distance between the amino groups of the propyl part of spermine; and (2) the orientation of phosphate groups in A‐DNA inside the groove is preferable for complex formation with spermine to the outside groove arrangement of the phosphates in B‐DNA. These conclusions are further confirmed by the calculations for DNA–propane diamine complexes.

Identification of a thymic inhibitor ('chalone') of lymphocyte transformation as a spermine complex.

CHALONES are defined as endogenous, tissue-specific but species nonspecific inhibitors of cell proliferation. Their potential use in the control of neoplasia is well recognised1–3. Circumstantial evidence for the existence of a lymphocyte chalone has been produced4–8, but neither its chemical nature nor its molecular weight have been satisfactorily ascertained. During our search for a lymphocyte chalone, an inhibitor of lymphocyte transformation has been reproducibly isolated from porcine thymic tissue. We report here that though the inhibitor was non-dialysable, its active moiety was identified biologically and chemically as spermine, molecular weight only 202. This accords with the formation in thymic extracts of a tightly bound spermine complex. As the complex displayed some tissue specificity it is possible that an unidentified tissue-specific material acts as a carrier for spermine. In relatively crude extracts of tissues it is probable that spermine-elicited inhibition swamps any authentic chalone activity.

Spermine stabilizes the conformation of tRNA Phe in crystals

Crystals from yeast tRNA Phe were dissolved and compared with tRNA Phe that had not been crystallized. A number of differences were found regarding the interaction with ethidium bromide, the melting point and the circular dichroic signal. These differences were assigned to the presence of spermine in the dissolved crystals indicating a transient stabilization of the conformation of tRNA Phe, probably as a tRNA Phe · spermine complex, after dissolving.