Extra Proton Research Articles

Band structure of odd-Arubidium isotopes in the interacting boson fermion model

Energy spectra and E2 matrix elements have been calculated by means of the interacting boson fermion model for /sup 79,81,83/Rb. A more schematic description obtained by assuming that the extra proton which is coupled to an even-even Kr core is in a pure g/sub 9/2/ particle state has been compared with calculations within a larger model space including the d/sub 5/2/ and g/sub 7/2/ particle states. We find that it is possible to achieve excellent agreement for both the schematic and the more detailed calculation as far as only level energies are concerned. However, the choice of the model space turns out to have a strong influence on the model parameters. Moreover, we find that B(E2) values differ considerably in both descriptions. We conclude that even if there is a large separation between shells, the mixing due to the strong core-particle quadrupole force does not allow for restricting the model space to a single j shell.

Nuclear magnetic resonance studies of codon-anticodon interaction in tRNA Phe: I. Effect of binding complementary tetra and pentanucleotides to the anticodon

The effect of codon-anticodon interaction on the structure of two tRNA Phe species was investigated by means of nuclear magnetic resonance spectroscopy. To this end n.m.r. † † Abbreviation used: n.m.r., nuclear magnetic resonance; p.p.m., parts per million. spectra of yeast and Escherichia coli tRNA Phe were recorded in the absence and the presence of the oligonucleotides U-U-C-A, U-U-C-G and U-U-C-A-G, which all contain the sequence UUC complementary to the anticodon sequence GAA. The spectra of the hydrogen-bonded protons, the methyl protons and the internucleotide phosphorous nuclei served to monitor the structure of the anticodon loop and of the tRNA in the tRNA-oligonucleotide complex. From the changes in the methyl proton spectra and in the phosphorous spectra it could be concluded that the oligonucleotides bind to the anticodon. Moreover it turned out that the binding constants obtained from these n.m.r. experiments were, within experimental error, equal to the values obtained with other techniques. Using the resonances of the protons hydrogen-bonded between the oligonucleotide and the anticodon loop the structure of the latter could be studied. In particular, binding of the pentanucleotide U-U-C-A-G, which is complementary to the five bases on the 5′ side of the anticodon loop, resulted in the resolution of four to five extra proton resonances indicating that four to five base-pairs are formed between the pentanucleotide and the anticodon loop. The formation of five base-pairs was confirmed by an independent fluorescence binding study. The resonance positions of the hydrogen-bonded protons indicate, that an RNA double helix is formed by the anticodon loop and U-U-C-A-G with the five base-pairs forming a continuous stack. This structure can be accomodated in the so-called 5′ stacked conformation of the anticodon loop, a structure that has been suggested earlier as an alternative to the familiar 3′ stacked conformation in the crystal structure models of yeast tRNA Phe. It turned out that structural adjustments of the anticodon loop to the binding of the oligonucleotides are propagated into the anticodon stem. The relevance of these results with respect to the mechanism of protein synthesis is discussed.

ChemInform Abstract: THE NATURE OF IRON IN AKAGANEITE (β‐FEOOH)

AbstractFür synthetische, in den Strukturkanälen C1′ enthaltende Akaganeit‐Proben sowie eine F′‐haltige Probe werden im Temp.‐Bereich 4‐295 K Mößbauer‐Spektren aufgenommen und auf der Grundlage zweier Oktaedertypen im Gitter, FeO3(OH)3 und FeO2(OH)4, gedeutet.

The nature of iron in Akaganéite (β-FeOOH)

The Mossbauer spectra of a size range of synthetic akaganeite (β-FeOOH) samples containing chloride, and one sample containing fluoride, in the structural tunnels, have been obtained over 4-295 K. At 295 K the spectra consist of overlapping paramagnetic doublets which indicate the presence of at least two sites for iron. Typical parameters for a spectrum of chloride-containing β-FeOOH fitted to two doublets are: (i) δ (relative to iron metal) 0.372 mm s-1, Δ 0.55 mm s-1, Г 0.27mm s-1; (ii) δ 0.375 mm s-1, Δ 0.94mm s-1, Г 0.33 mm s-1, with peak area ratios (i) : (II) of 60 : 40 for lath-shaped particles and 53 : 47 for spindle-shaped particles. At 77 K the spectra consist of overlapping magnetic hyperfine components which indicate the presence of at least three sites for iron, a three-component model giving internal magnetic fields of about 470 kOe, 460 kOe, and 435 kOe. The spectra of fluoride-containing β-FeOOH are very similar to those for chloride-containing β- FeOOH. The results are explained in terms of two types of octahedra within the lattice, FeO3(OH)3 and FeO2(OH)4, the extra proton in the second type balancing the charge on halide ions within the tunnels. Secondary effects may arise from the interaction of the halide ions with adjacent octahedra. The effects of modifying the surfaces of β-FeOOH particles (heating, phosphate sorption) are consistent with modification of the outer surfaces of the particles only, and it is not necessary to invoke the presence of large internal pores, of the order of 30Ǻ by 30Ǻ, as has been suggested by some earlier workers.

Primary reactions in crystalline salts of tartaric acids studied by ESR spectroscopy

Irradiated Rochelle salt and di-K-tartrate were examined by ESR spectroscopy in order to identify the primary products present at 77 K. For the deuterated Rochelle salt we have suggested a decay scheme for a primary species thought to be the oxidation product (K +) −O 2CCHODCHODCŌ 2(Na +). On the basis of 13C, 1H and 23Na hyperfine couplings, the extra proton coupling seen in protonated Rochelle salt and data from di-K-tartrate we have reinterpreted our earlier assignment of the 77 K spectrum. The new results indicate that the primary product seen at 77 K is the reduction product (K +) −O 2CCHODCHODC̄O 2D −1(Na +) which decomposes by water elimination to −O 2CCHODC̄HCO − 2. There is no detectable coupling to K + in di-K-tartrate.

In‐beam electron impact mass spectrometry of aliphatic alcohols

AbstractThe characteristics of the in‐beam electron impact mass spectra of six isomers of undecanol as well as several 1‐alkanols have been examined. In addition to the characteristic ions observed in the conventional electron impact spectra, the [2M+1]+, [2M+1‐H2O]+, [2M+1‐2H2O]+, [2M‐R or R′]+, [2M‐H2OR or R′]+, [2M2H2OR or R′]+ and [M+1H2O]+ peaks are common in the in‐beam electron impact mass spectra of the undecanol isomers of structure RCH(OH)R′. Deuterium labelling experiments have shown that the extra proton in the protonated dimer ions, [2M+1]+, originates from the hydroxy group. The processes which produce the important peaks in the high m/e regions are discussed.

Gated proton conduction via the coupling factor of photophosphorylation modified by N, N- orthophenyldimaleimide

The membrane bound coupling factor of photophosphorylation is studied after pretreatment of broken chloroplasts with the bifunctional N, N- orthophenyldimaleimide under energization of the thylakoid membrane by mild flashing light. The proton conduction of the membrane is monitored both via the electrochromic absorption changes and via selective pH-indicating dyes. It is found that the coupling factor, after interaction with N, N- orthophenyldimaleimide during the preillumination period, shortcircuits one of the two protons pumped inside after excitation of chloroplasts with one short flash of light. In contrast to the low proton conductivity of the unperturbed thylakoid membrane (relaxation time for a proton gradient > 5s), this extra proton channel leads to a partial relaxation of a proton gradient within a few ms. Although limited to only one proton per electron, this extra proton conducting pathway is not otherwise specific. It operates with protons resulting from both Photosystem I and Photosystem II activity. In addition it operates with protons already present in the internal phase before firing of the exciting light flash. These effects are prevented by the presence of ATP (but not GTP) during the preillumination period. It is suggested that the modified coupling factor is gated open by the light induced electric field across the thylakoid membrane while self closing after passage of one proton per activated coupling factor.

Electron spin resonance studies of methyl radicals trapped on 4A type zeolite

Three kinds of methyl radicals were observed with different heat treatments of Linde 4A type zeolite. The first is the normal methyl radical; the second is the abnormal methyl radical, type I, having additional coupling with one extra proton; and the third is the abnormal methyl radical, type II, having large coupling with one of the three protons. These three different radicals are stabilized on the zeolite heat treated at ca. 65, ca. 80, and ca. 250$sup 0$C, respectively. It was revealed by experiments using CD$sub 4$ that a hydrogen atom liberated from irradiated CH$sub 4$ is most probably stabilized on the zeolite surface and converted into H$sup +$, which causes the additional coupling noted in the abnormal methyl radical I. The fact that the $sup 13$C-hyperfine coupling of the abnormal methyl radical, type II, gives axial symmetric tensors and shows a trend of A/sub parallel/ (75.8 G) greater than A/sub perpendicular to/ (10.5 G) indicates that this methyl radical interacts with the surface through a 2P/sub pi/ unpaired-spin orbital and rotates about the C$sub 3$ symmetry axis. The relation of each type of methyl radical with the trapping environment as well as the probable geometry of each radical ismore » discussed. (auth)« less

ENDOR studies of the superhyperfine couplings of hydrogen bonded protons. II. Protonated radical anion in irradiated succinic acid single crystals

The carboxyl radical anion trapped at 77°K in an irradiated single crystal of succinic acid has been studied by ENDOR in order to determine if the anion is protonated. The ENDOR spectra showed that the anion exhibited hyperfine couplings to the two OH protons. The principal values of the two coupling tensors are nearly the same and the principal directions are accounted for by the structure of R–Ċ(OH)2, that is, the protonated form of the anion. The location of the extra proton suggests that the proton is transferred from the neighboring molecule across the hydrogen bridge.

Organoboranes in organic synthesis. II. The mechanism of the reaction of α,α'-dibromo ketones with organoboranes in the presence of base

The mechanism of the reaction of α,α-dibromocyclohexanones with organoboranes has been investigated, and is suggested to occur by attack of base on bromine in the ketone-borane adduct, followed by rate-determining alkyl group transfer from boron to carbon. Labelling studies show that the extra proton in the products comes from the solvent, tetrahydrofuran.

Structural Studies of Tryptophan Metabolites by X-ray Diffraction Method. I. The Crystal and Molecular Structure of 5-Hydroxy-Dl-Tryptophan

Abstract 5-Hydroxy-Dl-tryptophan was crystallized from a methanol solution in the monoclinic space group C2/c, with cell-dimensions of a=16.765, b=5.892, c=20.887 Å, and β=92.06°. The molecular structure and stereoconfiguration have been elucidated by the direct method for non-primitive space group. A Fourier map, calculated with the largest 198 normalized structure factors as Fourier coefficients, revealed the whole structure which was refined by the least-squares method. The molecule is a zwitterion as in the crystal structure of amino acids, each amino nitrogen atom having an extra proton. The indole ring plane forms a dihedral angle of 40° with that formed by an acid group. With respect to the conformation about the C(α)–C(β) bond, the orientation of C(β)–C(γ) bond is trans with respect to the C(α)–COO–. The molecules are arranged in double layers parallel to the ab-plane. The layer by polar groups is held together by a series of hydrogen bonds in a three-dimensional network, and by non-polar groups in the other layer, indole rings being stacked by van der Waals forces. The d-and l-forms of 5-hydroxytryptophan are hydrogen-bonded into two types of dimer related by the center of symmetry, one through N–H···O, and the other through O–H···O hydrogen bonding.

EXTRA COUPLING OF AN ETHYL RADICAL ADSORBED ON THE ZEOLITES

Abstract New ESR spectra were obtained from the irradiated ethane adsorbed on zeolites. The simulation method and an analysis indicate that the new spectra are those from ethyl radical having additional coupling with an extra proton.

Deuterium exchange at the 7-methyl group in 6,7,8-trimethyl-lumazine [6,7,8-trimethylpteridine-2(1H),4(3H)-dione]. An unusual example of general acid–general base catalysis

The rate of exchange of the hydrogen atoms in the 7-methyl group of 6,7,8-trimethyl-lumazine (I) at 34·5° has been followed by means of 1H n.m.r. spectroscopy. The reaction is subject to both general acid and general base catalysis, with Brönsted coefficients α= 0·46 (12 acids) and β= 0·45 (14 bases). The rate of the spontaneous reaction is extremely low and there is no evidence of a product term, [HA][A–], for the catalysis. The catalytic constants kHA and kA– are approximately equal when the acid–base pair used as buffer has a pKa of 2·8. The acid- and base-catalysed routes differ only by the presence of an extra proton in the former. This permits a comparison to be made of the ability [k(SH++ A–)] of the buffer anion A– to abstract a proton from the protonated substrate relative to its ability [k(S + A–)] to do so from the neutral substrate. The value of k(SH++ A–)/k(S + A–) is 102 in the case of compound (I), and since α+β for this reaction is close to unity, is almost independent of the buffer used. Other prototropic reactions that are also subject to general acid–base catalysis are analysed in the same way and it is shown that the value of k(SH++ A–)/k(S + A–) found in the present work is unusually low.

Some Odd Z Nuclei in the 63 ≤ A ≤ 89 Mass Region in the Framework of the Intermediate Coupling Model

The level structures of the nuclei 63Cu, 69Ga, 75As, 79Br, 83Rb, and 89Y are investigated in the framework of the unified model.Each nucleus is considered to consist of an even–even vibrating core and extra-core proton quasiparticle. The quasiparticle–core interaction Hamiltonian is assumed to be given by a dipole plus a quadrupole term. The coupling of a g9/2 state to the vibrating core leads to the formation of states of positive parity with [Formula: see text]. Such states with I up to 11/2+ have been recently observed in the nuclei under investigation. In the case of negative parity states the extra core proton quasiparticle is assumed to have available the p3/2, p1/2, and ƒ5/2 states. Many features of the investigated nuclei are explained by the model at least qualitatively. The present calculations do not exhaust the possibility of improved results. Future experimental data will be highly desirable not only for testing but also for improving the model.

Electron spin resonance studies of reduction by solvated electrons in liquid ammonia. Part III. Aromatic carboxylic acids

Electron attachment to series of ring-substituted aromatic carboxylate mono- and di-anions in liquid ammonia solution to give e.s.r. spectra of the corresponding paramagnetic transient intermediates has been accomplished by means of the rapid-mixing cell described in Part I. Benzoic, thiobenzoic, isophthalic, and terephthalic acids and the toluic, 4-methoxy-, and dimethylbenzoic acids yield the radical-anions, ArCO2n·, but the halogen-substituted acids shed halogen to yield C6H5CO22–·, with the exception of the fluoro-acids which initially yield the substituted radical-anion (although subsequent loss of F from p-fluorobenzoic acid occurs in the course of milliseconds). Two nitrodicarboxylic acids show unusual behaviour; the species produced initially in the flow system correspond to the parent molecule plus a hydrogen atom, the presence of the extra proton in the system being marked by an additional coupling of ca. 12 Oe; these entities change rapidly to more stable radicals with spectra attributable to the ‘normal’ radical-anions. Hückel and McLachlan calculations have been carried out on all the new radicals described.

The crystal and molecular structure ofl-ornithine hydrochloride

Crystals of ornithine hydrochloride, C 5 H 12 N 2 O 2 · HCl belong to the monoclinic space group P 2 1 with cell dimensions a = 4.99 Å, b = 8.00 Å, c = 10.00 Å and β = 97°. The number of molecules per unit cell is two. The structure has been solved by three-dimensional Patterson and heavy-atom Fourier syntheses. The hydrogen positions have been located from a three-dimensional difference Fourier synthesis. The positional coordinates of all the atoms, together with their temperature factors (anisotropic for non-hydrogen atoms and isotropic for hydrogen atoms), have been refined by three-dimensional least-squares method. The R value at the end of the refinement is 0.064. The bond lengths and bond angles of ornithine hydrochloride have been compared with those of other amino acids, particularly arginine dihydrate and lysine hydrochloride. The molecule is a zwitterion, with both the alpha and terminal amino nitrogen atoms accepting an extra proton each. The side chain of this molecule has a fully extended configuration. Both the amino nitrogen atoms assume tetrahedral configuration and interlink the molecules in the crystal by a three-dimensional network of hydrogen bonds of the types N–H···Cl − and N–H···O.

On the Heavy Primary Cosmic Ray Interactions in Nuclear Emulsions

The interactions of heavy primary particles in cosmic rays are analyzed by the method of nuclear emulsions. From this analysis, some characteristics of nuclear structure are obtained. The ratio of the number of fragment alpha particles to that of fragment protons produced by incident heavy primaries (Z between 6 and 9) is about 0.37 for N h ≤7 events, and this value is in good agreement with the results of other experiments. The transparency of medium nucleus is estimated to be about 30%. The relation between incident energies and average number of produced mesons is compared with other accerelator data. The experimental results are well interpreted from the view that the medium nucleus having charge 6 to 9 is constructed from a group of some complete helium nuclei if the charge of medium nucleus is evem (alpha particle model), while the odd charged medium nucleus is composed of some helium nuclei and a helium nucleus accompanied by an extra proton.

Photoinduced Paramagnetism in Solutions of Nitrobenzene in Tetrahydrofuran

ESR studies are reported of photoinduced paramagnetism in solutions of nitrobenzene in undeuterated and deuterated tetrahydrofuran (THF). The ESR spectrum exhibits a widely spaced set of identical triplets, and the extra proton hyperfine interaction (0.38 plus or minus 0.04 Oe) is due to a single alpha proton of the THF molecule. The experiments of Lagercrantz and Yhland with trinitrobenzene were also repeated, and the following mechanism for the production of the paramagnetic species is proposed: Light irradiation causes the nitro group to abstract an alpha hydrogen atom from the THF molecule, and the resulting THF free radicais rapidly dimerize or disproportionate, leaving a neutral nitrobenzene free radical in solution. The radical has a totai decay time of approximates 2 sec and is suspected to reside on an oxygen atom. (D.L.C.)

Extension of the Radioactive Series,Z=N±1

The radioactive positron emitters ${\mathrm{Si}}^{27}$, ${\mathrm{S}}^{31}$ and ${\mathrm{A}}^{35}$ were produced by 15-Mev alpha-particles while ${\mathrm{Sc}}^{41}$ was obtained by 8-Mev deutrons. The half-lives of these elements have been determined as 4.92\ifmmode\pm\else\textpm\fi{}0.1 seconds, 3.18\ifmmode\pm\else\textpm\fi{}0.04 seconds, 1.88\ifmmode\pm\else\textpm\fi{}0.04 seconds, and 0.87\ifmmode\pm\else\textpm\fi{}0.03 seconds, respectively. The upper limit of the energies of the positrons emitted by ${\mathrm{S}}^{31}$, ${\mathrm{A}}^{35}$, and ${\mathrm{Sc}}^{41}$ were measured and found to be 3.87\ifmmode\pm\else\textpm\fi{}0.15 Mev, 4.41\ifmmode\pm\else\textpm\fi{}0.09 Mev, and 4.94\ifmmode\pm\else\textpm\fi{}0.07 Mev, respectively. The Coulomb energies of the "extra proton" of the nuclei of the $Z\ensuremath{-}N=1$ were calculated according to two nuclear models. The variations in the Coulomb energies indicate a nuclear "shell" structure similar to that given by the Hartree model of the nucleus.