Assay for enkephalin-degrading peptidases in rat brain tissues by high-performance liquid chromatography with on-line post-column fluorescence detection

The activities of enkephalin-degrading peptidases such as enkephalinases A and B in rat brain tissues were simultaneously assayed by a high-performance liquid chromatographic method with fluorimetric detection with an automatic reaction system. Tyrosine and tyrosine-containing peptides produced enzymatically from the substrate, methionine-enkephaline, were separated by gradient elution on a reversed-phase column (TSK gel ODS-120T), and then converted into fluorescent derivatives for detection by reaction with hydroxylamine, cobalt(II) and borate reagents. The method permits the simple and sensitive detection of N-terminal tyrosine-containing fragments of the enkephalin peptide. The limits of detection are 5-20 pmol per assay tube for the N-terminal tyrosine-containing fragments. The enzyme activities in the regionally separated tissues were 54-191 pmol/min.mg protein for enkephalinase A and 79-153 pmol/min.mg protein for enkephalinase B, which were calculated from the formation of Tyr-Gly-Gly and Tyr-Gly, respectively, during the enzyme reaction.     

Aromatic hydroxylation with peroxymonophosphoric acid

Aromatic hydroxylation of mesitylene, phenol and anisole (ArH) with peroxymonosphosphoric acid (H₃PO₅) in acetonitrile has been studied. H₃PO₅ is shown to be an effective reagent for aromatic hydroxylation, the reactivity being comparable to that with CF₃CO₃H. Mesitylene gives mesitol (over 70%). The hydroxylation with H₃PO₅ is ca 100 fold faster than that with MeCO₃H or PhCO₃H. The rate equation is: v = k₂[ArH][H₃PO₅] instead of our previous one. The oxidation is catalyzed by H₂SO₄, giving a linear plot of log k₂ vs H₀ with a slope of 1.26 for phenol and 1.17 for mesitylene.     

Preparation of optically active 1-acetoxy-2-aryloxypropionitriles and its application to a facile synthesis of (S)-(−)-propranolol

(S)-1-acetoxy-2-aryloxypropionitriles were synthesized by an asymmetric hydrolysis of the racemates with an enzyme. (S)-propranolol, a typical β-adrenergic blocker, was synthesized from (S)-1-acetoxy-2-α-naphthyloxypropionitrile in two steps.     

Reflection spectra of orthorhombic indium iodide

The reflection spectra of InI single crystal have been measured using linearly polarized light. Pronounced anisotropy is observed between two directions of polarization E ∥ c and E ∥ a. The first peak at 2.018 eV for E ∥ c is direct allowed exciton transition with binding energy 4.3 meV. The E ∥ a spectrum suggests that the transition is forbidden.     

Study on interactions of endocrine disruptors with estrogen receptor-beta using fluorescence polarization.

In this study, we developed a rapid, simple and homogeneous human recombinant estrogen receptor-beta (hrER-beta) binding assay method using fluorescence polarization (FP) by applying a fluorescent ligand, fluorescein-labeled estradiol (F-E2). A Scatchard plot and a Hill plot analysis of the saturation binding assay using F-E2 and hrER-beta were studied. F-E2 showed a high affinity for hrER-beta, the dissociation constant was 5.53 nM, indicating that F-E2 is applicable to the hrER-beta binding assay. Competitive binding assays using F-E2, in which the FP values decreased upon the addition of compounds (competitors) were carried out to evaluate the binding characteristics of compounds with and without biological activities to hrER-beta. Twenty-one compounds, such as hormones, pharmaceuticals, industrial chemicals and phytoestrogens, were examined. The obtained sigmoidal inhibition curves were transformed into pseudo-Hill plots and the concentrations at 50% inhibition (IC50) and Hill coefficients, the degree of cooperativity in ER-ligand binding, were obtained from the regression equations. Antagonists exhibited larger Hill coefficients than agonists, showing the correlation between the Hill coefficients and the estrogenic/antiestrogenic activities.     

The 4s- and 4p- XPS spectra of Xe, XeF2 and XeF4

The 4s- and 4p- XPS spectra of Xe gas, XeF₂ molecule and XeF₄ molecule are calculated by an ab-initio atomic many-body theory. The 4s-peak and the prominent ‘4p’-peak are predicted well by the present theory. In XeF₂ and XeF₄ the spectral lines observed below the 4d-double ionization threshold are the 4d⁻²4f multiplet states strongly perturbed by the interaction with the initial 4p_1/2-hole state. They are very similar to the spectral lines which emerge with an increase in atomic number (e.g. Ba).     

A mild methylation of alcohols with diazomethane catalyzed by silica gel

Alcohols including prostaglandins, geraniol, and carbohydrate, can easily be methylated with diazomethane in the presence of silica gel.     

A stereocontrolled synthesis of (−)-bestatin from an acyclic allylamine by iodocyclocarbamation

1,2-Asymmetric induction of iodocyclocarbamation is described by using allylamines 2 and 6 and the method has been successfully applied to a stereocontrolled synthesis of bestatin.     

Einfluß des Druckes auf die Schmelztemperaturen von Polyäthylen-Fraktionen

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