Molecular design of potent inhibitor specific for cathepsin B based on the tertiary structure prediction.

To design a potent inhibitor specific for cathepsin B (rat liver), the tertiary structure was predicted based on the crystal structure of the papain complexed with (+)-(2S,3S)-3-(1-[N-(3-methylbutyl)amino]leucylcarbonyl)oxirane-2- carbolylic acid (E-64-c), a thiol protease inhibitor. Taking advantage of the structural characteristics of the predicted active site, seventeen inhibitors were chemically synthesized by molecular modeling, and one of them, N-(L-3-trans-propylcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-p rol ine (CA-074) was shown to be the first potent inhibitor specific for cathepsin B. The relationship between the structure and inhibitory activity is discussed based on the model structure of the cathepsin B-inhibitor complex.     

On a dendrite generated by a zero-dimensional weak self-similar set

Let S be a zero-dimensional, perfect, compact weak self-similar set generated in dendrite X by a family {f_j} of weak contractions from X to itself. Decomposition space D_f of S due to a continuous mapping f from S onto X is also a dendrite. In the dendrite D_f, there exists a zero-dimensional, perfect, compact weak self-similar set S¹ based on a family each of which is topologically conjugate to f_j. Decomposition space D_f¹ of S¹ due to a continuous mapping f¹ from S¹ onto D_f is again a dendrite. In this manner, through the successive formation of weak self-similar set, we can obtain a sequence X,D_f,D_f¹,… of dendrite any pair in which are mutually homeomorphic.     

Mutual Kinetic Resolution in Aldol Condensation between 2-Phenylpropanal and 4,5-Dihydro-5-methyl-2-(trimethylsiloxy)-3-(trimethylsilyl)furan

The titanium(IV) chloride-mediated aldol condensation between title compounds proceeds with high diastereoselectivity (Cram) to give $\text{3a}$ exclusively (99% purity).     

α + 14C molecular states in 18O

The possible existence of α + ¹⁴C molecular states in ¹⁸O is investigated in a coupled-channel orthogonality-condition model. Comparison with experiment, specifically E1, E2 transition probabilities and reduced α-widths, shows that the assumption of a single molecular configuration for the so-called dipole band is inappropriate. The result of calculation further makes it possible to single out a few molecular bands in ¹⁸O.     

A homotopy equivalence that is not homotopic to a topological embedding

An open subset W of Sⁿ, n 6 or N = 4, and a homotopy equivalence ƒ: S² × S^{n − 4} → W are constructed having the property that ƒ is not homotopic to any topological embedding.     

237Np and 57Fe Mössbauer study of NpFeGa5

⁵⁷Fe and ²³⁷Np Mössbauer ōmeasurements have been performed for NpFeGa₅, which is one of the so-called neptunium 1-1-5 compounds. The ⁵⁷Fe Mössbauer spectra below T _N = 118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the ⁵⁷Fe nucleus is determined to be 1.98 ± 0.05 T at 10 K. From the ²³⁷Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the ²³⁷Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μ_B using the Np atomic magnetic moment of 0.86 μ_B determined by the neutron diffraction study.     

Ultraviolet photoemission spectroscopy of (TaSe4)2I

The vacuum ultraviolet photoemission spectra of quasi-one-dimensional charge density wave ( CDW ) system, (TaSe₄)₂I, were measured for photon energies between 32 and 100 eV at room temperature ( in the normal phase ) and at about 100 K ( in the CDW phase ). The spectrum of Ta 4f core-levels has shown no additional splitting due to the two different Ta sites. The spectra of the valence and conduction bands have revealed the resonant enhancement for the excitation of the Ta 5p core states, which demonstrates the remarkable hybridization of Ta 5d orbitals with Se 4p orbitals with binding energies smaller than 4 eV. In the CDW phase, the partial cross section decreases for both Ta 5d bands and Se 4p bands with Ta 5d components.     

Theoretical study of resonant-tunneling and confining phenomena with mass variation in unsymmetrical rectangular double-barrier structures

Analytical expressions for the transmission coefficient and the resonance condition in unsymmetrical rectangular double-barrier structures are derived theoretically by taking into account the mass difference between well and barrier layers. It is found that resonant tunneling with a transmission peak equal to 1 (unity resonance) and resonant tunneling with a transmission peak less than 1 (below unity resonance) may occur in the unsymmetrical double-barrier structures. Two independent conditions are required for unity-resonant transmission: One is the Phase-Difference Condition for Resonance (PDCR) and the other is the Maximum Condition for the Peak Value (MCPV). The below-unity resonant transmission occurs when only condition PDCR holds. It is believed that the two conditions are useful for calculating values of the transmission coefficient and the resonance energy for the unsymmetrical double-barrier structures. They may be useful for resonant tunneling-device fabrication. Furthermore, wave functions of an electron at resonance level are calculated and the confining phenomenon is confirmed.