Hydrophobic scale: a second parameter to elucidating various specific ligand-protein interactions

In the sequence Fourier analysis (SFA) of specific interactions such as those between fibroblast growth factors (FGFs)/FGF receptors (FGFRs), bone morphogenetic proteins (BMPs)/BMP receptors (BMPRs), or tumor repressor protein p53/mouse double minute 2 homolog (MDM2), the characteristic frequency peak(s) could be observed with the hydrophobic scale for 20 amino acids as well as 4 nucleotides as the physicochemical parameter, but not successfully with the absolute electronegativity scale. This result implies that these two independent scales should be appropriately selected in various specific ligand-protein interactions, though the critical difference has to be determined.     

Interpretation of Hund's multiplicity rule for the carbon atom

Hund's multiplicity rule is investigated for the carbon atom using quantum Monte Carlo methods. Our calculations give an accurate account of electronic correlation and obey the virial theorem to high accuracy. This allows us to obtain accurate values for each of the energy terms and therefore to give a convincing explanation of the mechanism by which Hund's rule operates in carbon. We find that the energy gain in the triplet with respect to the singlet state is due to the greater electron-nucleus attraction in the higher spin state, in accordance with Hartree-Fock calculations and studies including correlation. The method used here can easily be extended to heavier atoms.     

Internal Rotation of the Hydroxyl Group in Isopropanol and the Chirality of the Gauche Form: Fourier Transform Microwave Spectroscopy of (CH(3))(2)CHOD

The rotational spectrum of the deuterated isopropanol (CH(3))(2)CHOD has been observed by Fourier transform microwave spectroscopy and analyzed to yield tunneling splitting of 4431.4613 (17) MHz, between the antisymmetric and the symmetric gauche forms, which is much larger than the 2400 MHz estimated from the internal-rotation potential function reported in the literature. The potential function for the OH internal rotation has been examined in view of the discrepancy between the observed and estimated tunneling splitting, and it was accounted for by taking into account isotope effects on the potential constants. The deuterium quadrupole coupling effect has been included together with the Coriolis terms in the off-diagonal block of the Hamiltonian matrix for the gauche form. The deuterium quadrupole coupling constants obtained for the trans form were employed to calculate the components of the coupling constants as functions of the internal-rotation angle, and the components at around 120 degrees were compared with the values observed for the gauche form, thereby leading to unambiguous determination of the signs of the constants in the off-diagonal block; the signs are not obtainable from an ordinary analysis of the rotational spectra. The chirality of the gauche form was discussed by placing special emphasis on the effect of intermolecular interactions between two chiral molecules. Copyright 2001 Academic Press.     

Japanese monkeys perceive sensory consonance of chords

Consonance/dissonance affects human perception of chords from early stages of development [e.g., Schellenberg and Trainor, J. Acoust. Soc. Am. 100, 3321-3328 (1996)]. To examine whether consonance has some role in audition of nonhumans, three Japanese monkeys (Macaca fuscata) were trained to discriminate simultaneous two-tone complexes (chords). The task was serial discrimination (AX procedure) with repetitive presentation of background stimuli. Each tone in a chord was comprised of six harmonics, and chords with complex ratios of fundamental frequency (e.g., frequency ratio of 8:15 in major seventh) resulted in dissonance. The chords were transposed for each presentation to make monkeys attend to cues other than the absolute frequency of a component tone. Monkeys were initially trained to detect changes from consonant (octave) to dissonant (major seventh). Following the successful acquisition of the task, transfer tests with novel chords were conducted. In these transfer tests, the performances with detecting changes from consonant to dissonant chords (perfect fifth to major seventh; perfect fourth to major seventh) were better than those with detecting reverse changes. These results suggested that the consonance of chords affected the performances of monkeys.     

Effect of the moisture content in aerosol on the spray performance of Stmerin D HFA preparations

Stmerin D, a pressurized metered dose inhaler (MDI) for treatment of asthma, contains CFCs (chlorofluorocarbons) as a propellant. For the CFC replacement study, two formulations were prepared using hydrofluoroalkanes (HFA-134a and HFA-227) and the effect of storage on the spray performance was investigated under accelerated stress conditions. Drug stability, moisture content and spray performances such as the emitted dose uniformity and aerodynamic particle size distribution were evaluated. Drug content did not change after 3 months storage at 40 degrees C/75% RH. However, the emitted dose uniformity varied and the respirable fraction (RF) was reduced remarkably. While stored at 40 degrees C/ambient for 3 months, no change was observed in either drug content or spray performances. This study clarified that the moisture content in the canister played an important role on the spray performance, and it changed not only the emitted dose uniformity but also the particle size distribution. Consequently, in order to improve the stability of the spray performance of aerosol prepared with HFAs, moisture permeation into the canister must be controlled.     

Establishment of hybrid-derived offspring populations in the Ohomopterus ground beetles through unidirectional hybridization

An approach to deduce the mechanism of stabilization of the hybrid-derived populations in the Ohomopterus ground beetles has been made by comparative studies on the phylogenetic trees of the mitochondrial and nuclear DNA. A phylogenetic tree based on the internal transcribed spacer (ITS) of nuclear ribosomal gene roughly reflects the relations of morphological species group, while mitochondrial NADH dehydrogenase subunit 5 (ND5) gene shows a considerable different topology on the tree; there exist several geographically-linked lineages, most of which consist of more than one species. These results suggest that the replacement of mitochondria has occurred widely in the Ohomopterus species. In most cases, hybridization is unidirectional, i.e., the species A (♂) hybridized with another species B (♀) and not vice versa, with accompanied replacement of mitochondria of A by those of B. The results also suggest that partial or complete occupation of the distribution territory by a hybrid-derived morphological species. The morphological appearance of the resultant hybrid-derivatives are recognized as that of the original species A. Emergence of a morphological new species from a hybrid-derived population has been exemplified.     

Infrared vibrational autodetachment spectroscopy of microsolvated benzonitrile radical anions

Vibrational spectra of microsolvated benzonitrile radical anions (C6H5CN- -S; S = H2O and CH3OH) were measured by probing the electron detachment efficiency in the 3 microm region, representing resonance bands of autodetachment via OH stretching vibrations of the solvent molecules. The hydrogen-bonded OH band for both the cluster anions exhibited a large shift to the lower energy side with approximately 300 cm-1 compared to those for the corresponding neutral clusters. The solvent molecules are bound collinearly to the edge of the CN group of the benzonitrile anion in the cluster structures optimized with the density functional theory, in which the simulated vibrational energies are in good agreement with the observed band positions. Natural population analyses were performed for a qualitative implication in changes of solvent orientation upon electron attachment. Asymmetric band shapes depending on the vibrational modes are discussed with respect to dynamics of the autodetachment process from a theoretical aspect incorporated with density functional calculations.     

A remark on the transformation formula of theta functions associated to positive definite quadratic forms

Let L be a positive Z-lattice with level N = cd, (c, d) = 1. Then the Fourier expansion at cusp $\text{1}\text{d}$ of the theta function associated to L is a theta function associated to L₁, where a lattice L₁ is defined by Z_pL₁ = Z_pL for $\text{p?c}$, Z_pL₁ = the dual of Z_pL for p | c.     

Stability and vibrational spectra of toroidal isomers of C 240

To study the thermodynamic and mechanical stability of toroidal isomers of C ₂₄₀, we use a semi-empirical tight-binding theory and calculate their electronic structure, cohesive energy and vibrational spectra within the harmonic approximation. From these, we deduce their free energy at temperatures up to 1500K. The results are also compared to the isomer with icosahedral symmetry. Finally, we discuss within this approach, their stability and abundance.