Colorimetric assay for lysozyme using Micrococcus luteus labeled with a blue dye, Remazol brilliant blue R, as a substrate.

Micrococcus luteus (M. lysodeikticus) labeled with Remazol brilliant blue R (blue ML) was prepared as a novel substrate for the colorimetric assay of lysozyme. The treatment of the labeled substrate with lysozyme resulted in the release of soluble blue products which can be easily measured spectrophotometrically at 600 nm. The blue color was most efficiently released at pH 7 and ionic strength of 0.2 on incubation with hen lysozyme at 40 degrees C. A new colorimetric method for the assay of lysozyme using this substrate was developed. The assay system gave a linear dose-response curve, and as little as 0.1 microgram of human lysozyme (1 microgram/ml, 100 microliters) can be detected. The present method is more convenient and reproducible than the conventional lysozyme assay with bacterial cells. Application of the system to the determination of lysozyme in human serum is described.     

Evaluation of dissociation constants of ammonium ion in aqueous lithium perchlorate and lithium chloride-sodium chloride mixed solutions

The Pitzer approach has been applied to the evaluation of dissociation constants of ammonium ion in lithium perchlorate and lithium chloride-sodium chloride mixed solutions at 25°C. The calculated values showed good agreement with the observed values, provided all the higher-order interaction terms ('s and 's) concerned were introduced. The unknown (NH₄LiClO₄) value was determined from the isopiestic measurements of NH₄ClO₄–LiClO₄ mixed solutions. Parameters in the Pitzer formalism for ammonia-ion interactions involved in LiCl and NaCl media were determined by use of the activity coefficients of ammonia measured in LiCl–NaCl mixed solutions by a transpiration method.     

Syntheses and degradations of fluorinated heterocyclics III. Perfluoroalkyl and perfluoroalkylether-1,3,4-oxadiazoles

2,5-Bis(perfluoro-n-heptyl)-, 2-perfluoroalkylether-5-perfluoro-n-heptyl-, and 2,5-bisperfluoroalkylether-1,3,4-oxadiazoles were synthesized and characterized. 2,5-Bis(perfluoro-n-heptyl)-1,3,4-oxadiazole was thermally and hydrolytically stable at 325°C; however, in the presence of air, degradation took place at 235°C. The perfluoroalkylether analogue exhibited thermal and hydrolytic stability at 325°C; it was found to be unaffected by Jet-A fuel and air at 235°C. At 325°C in air some degradation occured as evidenced by volatiles production, oxygen consumption, and 96% starting material recovery.     

Involvement of human small fragment nuclease in the resistance of human cells to UV-C-induced cell death

Human small fragment nuclease (Sfn) is one of the cellular proteins that were reported to degrade small, single-stranded DNA and RNA. However, the biological role of Sfn in cellular response to various stressors such as UV-C (mainly 254 nm wavelength ultraviolet ray) remains unclear. We have examined whether modulation of human SFN gene expression affects cell survival capacity against UV-C-induced cell death, analyzing colony survival ability in UV-C-sensitive human RSa cells treated with short double-stranded RNA (siRNA) specific for SFN messenger RNA (mRNA). The expression levels of SFN mRNA in the siRNA-treated RSa cells decreased to about 15% compared with those in the control siRNA-treated cells. The siRNA-treated RSa cells showed lower colony survival and higher activity of caspase-3 after UV-C irradiation than the control siRNA-treated RSa cells. Furthermore, the removal capacity of cyclobutane pyrimidine dimers (CPD) in the siRNA-treated RSa cells decreased compared with the control siRNA-treated RSa cells. There was no difference in the colony survival and CPD removal capacity after UV-C irradiation between the control siRNA-treated RSa cells and mock-treated RSa cells. These results suggest that SFN expression is involved in resistance of RSa cells to UV-C-induced cell death through the roles it plays in the DNA repair process.     

State of titanium in Ti-containing silica and silicalite catalysts in relation to their oxidation activity

The nature of active titanium species for epoxidation of olefins with H₂O₂ and t-butyl hydroperoxide has been investigated for titanium silicalite (TS-1), titania silica (TiO₂/SiO₂) prepared by a sol-gel method, and titanium oxide supported on silica by a CVD method (TiO₂/SiO₂-CVD). IR and XANES analyses suggested that Ti in TiO₂/SiO₂ and TiO₂/SiO₂-CVD has a tetrahedral configuration bonded to SiO₂ and that in TS-1 has a configuration composed of >Ti=O or related to it. Their configurations are closely related to their reactivities for epoxidation of olefins in which the former works with t-butyl hydroperoxide and the latter with H₂O₂.     

Two-color double resonance in the four-photon ionization of nitric oxide

We have measured the two-color double resonance enhanced four-photon ionization and the fluorescence de-enhanced spectra of nitric oxide by using two tunable pulsed dye lasers. The spectra show clear structure in the third-photon (8.2 eV) region. Also discussed is the multiphoton ionization mechanism in the resonance state.     

Separation of gallic acid from Cornus officinalis Sieb. et Zucc by high-speed counter-current chromatography

Gallic acid was separated from a n-butanol extract of the fruit of Cornus officinalis Sieb. et Zucc by high-speed countercurrent chromatography in two steps using two solvent systems composed of ethyl-acetate-ethanol n-butanol-water (5:1.8:6, v/v/v) and ethyl acetate-ethanol-water (5:0.5:6, v/v/v) successively. From 1 g of n-butanol extract the method produced 60 mg of gallic acid at a purity of 97%.