Amino acids and peptides. XXIX. Synthesis of peptide fragments related to active center of eglin c and studies on the relationship between their structure and their inhibitory activity against cathepsin G and alpha-chymotrypsin

H-Ser-Pro-Val-Thr-Leu-Asp-Leu-Arg-Tyr-OMe, corresponding to the sequence 41-49 of eglin c, inhibited human leukocyte cathepsin G and alpha-chymotrypsin. In order to gain further insight into the relationship between the structure and the inhibitory activity against cathepsin G and alpha-chymotrypsin, peptide fragments related to the above nonapeptide were synthesized by a conventional solution method and their inhibitory activities were examined. The smallest peptide which exhibited inhibitory effects on the above enzymes was H-Pro-Val-Thr-Leu-OMe, corresponding to the sequence 42-45 of eglin c.     

Phase transition in the mixed state of Bi2Sr2CaCu2Oy observed by local and macroscopic magnetometry

In Bi₂Sr₂CaCu₂O_y under magnetic fields along the c-axis, both the local and the macroscopic magnetization show clear steps indicating the first order phase transition (FOPT) in the vortex lattice (VL). Local measurements have revealed that the FOPT occurs from the center of the sample owing to the field inhomogeneity originated from the geometrical effect. The heights of the steps are strongly suppressed in local measurements by the demagnetization effect. With decreasing temperature, the irreversibility in the magnetization just below the step begins to increase and is smoothly connected to the second peak at low temperatures.     

In-plane force constants of the peptide group: Least-squares adjustment starting from ab initio values of N-methylacetamide

Least-squares adjustment of the force constants of N-methylacetamide belonging to the A′ symmetry block was carried out starting from the force constant values obtained by an ab initio SCF MO calculation with the 4–31G basis set. Fourteen diagonal force constants were adjusted by the use of 122 vibrational frequencies of 9 isotope derivatives in the liquid state observed in the region 2000-100 cm^?1. Here, all the off-diagonal elements were fixed at the initial values calculated with the 4–31G basis set. The greatest difference between the observed and calculated frequencies was 30 cm^?1, and the differences for 94 modes were less than 10 cm^?1. Most of the force constatns of bond stretching modes were reduced by 5–10%, and those of angle deformation modes by 20–30% in the course of the least-squares adjustment. The CO stretching force constant was lowered by 30% in the adjustment, and this is understandable because the adjustment involves the effect of bringing the peptide group from a free to a hydrogen-bonded state.     

Microwave spectrum of 15N16O2 in the ground state

¹⁵NO₂ (88 lines) in the ground state has been observed in the microwave spectral region up to 170 GHz. The least squares analysis gave the higher order distortion terms of rotational and spin-rotational Hamiltonian.     

Raman spectra of amorphous SiC

It has been found that the condition of the sample preparation exerts large influence on the structural disorder of the films. For the sample prepared by sputtering method, the dependence of CC band on substrate temperature T_s and partial pressure of SiH₄ during the sputtering has been measured.     

Absorption and emission spectroscopic characterisation of F<Subscript>3</Subscript><Superscript>-</Superscript> colour centers in a LiF crystal

For a LiF crystal containing F₃ (R₁, R₂), F₂, F₃ ⁺, F₄ (N₁, N₂), F₃ ^-, and F₂ ^- colour centers the absorption and emission spectroscopic behaviour of the F₃ ^- centers is studied. The absorption cross-section spectrum and the number density of F₃ ^- centers are extracted from saturable absorption and transmission measurements. Additionally fluorescence quantum distribution measurements and fluorescence lifetime measurements are carried out to determine the stimulated emission cross-section spectrum and the fluorescence quantum yield of the F₃ ^- centers. Fluorescence excitation spectroscopy reveals the presence of an absorption band with its absorption peak around 700 nm (called R ₁ band) in addition to the ground-state to first excited-state F₃ ^- center absorption band centered at 800 nm (called R ₂). PACS 61.72.Ji; 78.40.Ha; 78.55.Fv     

Pyrolysis of amines: Infrared spectrum of propargylimine

Propargylimine was detected in the gas phase for the first time. The molecule was produced by the pyrolysis of dipropargylamine, and examined by a Fourier transform infrared spectrometer. The production of this molecule was also confirmed by microwave spectroscopy. Identification of the molecule is supported by an ab initio MO calculation for its vibrational frequencies and rotational constants.