Asymmetric sulfoxidation and amine binding by H64D/V68A and H64D/V68S Mb: mechanistic insight into the chiral discrimination step

The H64D/V68A and H64D/V68S mutants of Myoglobin are found to oxidize thioanisole with high enantioselectivity and reactivity. These mutants are also capable of enantioselective binding of alpha-methylbenzylamine, which mimics an expected sulfoxidation intermediate. The kinetic study of the amine binding shows that the Fe-O bond cleavage in the intermediate may be the chiral discrimination step of the sulfoxidation.     

Antiinflammatory effect of Curcuma xanthorrhiza Roxb, and its active principles

The rhizomes of Curcuma xanthorrhiza Roxb, are used in Indonesian folk medicine as cholagogues, aromatic stomachics, analgesics, a rheumatic remedy, etc. The present study was carried out to elucidate the antiinflammatory effect of the methanol extract obtained from these rhizomes and its active principles. The methanol extract was partitioned between ether and water, and then the ether-soluble fraction was extracted with n-hexane. The n-hexane-soluble fraction was chromatographed (fr. I-IV), fr. II was rechromatographed (fr. V-VII), and then fr. V was rechromatographed (fr. VIII-X) by silica gel column chromatography. The antiinflammatory activity of these fractions was investigated on carrageenin-induced edema in rats and acetic acid-induced vascular permeability as well as the writhing symptom in mice. The methanol extract (p.o.) showed both an antiinflammatory activity and an analgesic activity and these activities shifted successively to the ether-soluble fraction, the n-hexane-soluble fraction, fr. II, V and IX. The chemical structure of fr. IX was identified as germacrone. These results suggest that the antiinflammatory action of Curcuma xanthorrhiza is the result of the germacrone that it contains.     

Simultaneous determination of rhenium,osmium and iridium in meteoritic samples by neutron activation analysis using simple and effective radiochemical procedures

Simple and effective procedures for the determination of Re, Os and Ir by radiochemical neutron activation analysis are presented. Those elements are separated individually by distillation (for Os) and anion exchange techniques (for Re and Ir) for a single specimen. Reproducibilities of the data obtained by the present procedures are evaluated by replicate analyses of the Allende meteorite sample, and are deduced to be 3% for Re, 6% for Os and 4% for Ir (1). Detection limits for the present procedures are calculated to be 1 ppb for Re, 20 ppb for Os and 5 ppb for Ir. These procedures were applied to Antarctic meteorites and proved to work very effectively for the determination of trace Re, Os and Ir in chondrite meteorites.     

Neutron activation analysis of biologically essential trace elements in environmental specimens using pyrrolidinedithiocarbamate extraction

A new radiochemical group separation method using APDC reagent in the extraction procedure has been developed. The method has been applied to the radiochemical separation for activated biological samples and also to the preconcentration technique for sea water samples. The transition elements are extracted into chloroform phase from the pH 3.0 aqueous phase and only manganese is subsequently extracted from the pH 7.0 aqueous phase. The validity of the method is demonstrated by analyzing the NBS standard reference materials. In the specimens preconcentrated from the sea water samples adjusted pH to 5.5, vanadium, manganese, copper and zinc can be determined.     

Separation of single-stranded oligonucleotides on polyvinyl alcohol gel column

Summary Separation mechanisms for single-stranded oligodeoxyribo-or oligoribonucleic acid fragments were explored on an Asahipak polyvinyl alcohol gel column (GS-320) by use of sequential isomers of such molecules. Substrates having different base numbers were found to be separated by size-exclusion chromatography while those having the same numbers with different base sequences were isolated by use of the reversed-phase mode. By using those dual modes, a limit for the separation of the samples was found to arise because one mode shifted the peaks of the substrates in the sense opposite to the shift resulting from the other mode and it was found that when substrates had less than nine bases, the solutes eluted separately.     

Syntheses of (±)-pyrenophorin and (±)-colletallol

Pyrenophorin $\text{1}$ and colletallol $\text{3}$ were synthesized in their racemic forms from the corresponding hydroxycarboxylic acids $\text{9}$ and $\text{14}$ via stereoselective formation of the requisite trans double bonds after macrocyclization.     

Broken symmetry solutions of the extended Hubbard model

This paper describes a group theoretical classification of the unrestricted Hartree–Fock (UHF ) solution of the extended Hubbard model including nearest-neighbor repulsion and exchange interactions. We derived systematically all types of the broken symmetry solution with a single-order parameter for the ordering vector Q = (π,π). It is shown that there are four nonmagnetic states: a charge density wave (CDW), a charge current wave (CCW), and two bond-order waves (BOW), and five magnetic states: an ordinary antiferromagnetic state (AF), a spin current wave (SCW), two axial spin bond-order waves (ASBOW), and an helical spin bond-order wave (HSBOW). We showed that these phases can be derived naturally from the irreducible decomposition of the Fourier transformed interaction and the self-consistent field (SCF ) condition. Some numerical results are given for the half-filled case.     

Vibrational spectra and rotational isomerism of simple dialkyl dithioesters and N-acylglycine ethyl dithioesters,thiolesters, and dioxygenesters

Simple dialkyl dithioesters and N-acylglycine ethyl dithioesters have been investigated by Raman, resonance Raman and infrared spectroscopies. Based on the data of isotopic substituted derivatives and a normal coordinate analysis, vibrational assignments have been proposed for methyl dithioacetate. Raman spectra of ethyl dithioacetate(CH₃C(=S)S

CH₂CH₃) and methyl dithiopropionate (CH₃CH₂

C (=S)SCH₃) have provided fundamental knowledge on rotational isomerism about the bonds indicated. Raman, resonance Raman and FTIR spectroscopic studies on N-acylglycine ethyl dithioesters indicated the coexistence of three conformers in solution and a combined x-ray crystallographic-resonance Raman spectroscopic approach has been used to set up precise structure-spectra correlations for these conformers. The corresponding conformational states of N-acylglycine thiolesters and dioxygenesters are also discussed briefly.