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1.
The molybdenum and tungsten dinitrogen-organonitrile complexes trans-[M(N2)(NCR)(dppe)2] (2, M=Mo; 4, M=W; R=Ph, C6H4Me-p, C6H4OMe-p, Me; dppe=Ph2PCH2CH2PPh2) underwent double protonation at the nitrile carbon atom with loss of N2 and a change in oxidation state to +4 on treatment with hydrochloric acid to afford the cationic imido complexes trans-[MCl(NCH2R)(dppe)2]+. The solid-state structure of trans-[WCl(NCH2CH3)(dppe)2][PF6]·CH2Cl2 was determined by single-crystal X-ray analysis. Protonation of complexes 2 by fluoroboric acid or hydrobromic acid also formed the similar imido complexes trans-[MoX(NCH2R)(dppe)2]+ (X=F, Br). In contrast, the dinitrogen complex trans-[Mo(N2)2(dppe)2] reacted with two equiv. of benzoylacetonitrile, a nitrile with acidic CH hydrogen atoms, to give the nitrido complex trans-[Mo(N)(NKCCHCOPh)(dppe)2] (12), which was accompanied by evolution of dinitrogen and the formation of 1-phenyl-2-propen-1-one in high yields. For complex 12, the zwitterionic structure, where the anionic enolate ligand PhC(O+)=CHCN coordinates to the cationic Mo(IV) center through its nitrogen atom, was confirmed by spectroscopic measurements and single-crystal X-ray analysis. A unique intermolecular aromatic C---HO hydrogen bonding was observed in that crystal structure. Complex 12 is considered to be formed via the cleavage of the CN triple bond of benzoylacetonitrile on the metal. A reaction mechanism is proposed, which includes the double protonation of the nitrile carbon atom of the ligating benzoylacetonitrile on a low-valent molybdenum center. 相似文献
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Tomonori Murakami Kenji Hiraoka Takeshi Mikami Tatsuji Matsumoto Susumu Katagiri Kunihiro Shinagawa Masuko Suzuki 《FEMS microbiology letters》1993,107(2-3):179-183
Abstract Flagellar antigen of Bacillus cereus H.1 was purified and tested for serodiagnostic antigen by ELISA. The antibody against the flagellar antigen of B. cereus H.1 reacted not only with the homologous specific antigen but also reacted with the flagellar antigens of 23 strains of B. cereus . This common flagellar antigen of B. cereus was found to be due to 61-kDa protein by SDS-PAGE and immunoblot assay. Monoclonal antibody H15A5 against common antigenic epitope of B. cereus also reacted with flagellar antigens of 21 strains of Bacillus thuringiensis by ELISA. This monoclonal antibody reacted with the 61-kDa protein of the flagella of B. cereus H.1 and H.2 and B. thuringiensis Kurstaki HD1, Alesti and Aizawai juroi by immunoblot analysis. These results indicated that the common antigenic epitope of the 61-kDa protein existed in the flagella both of B. cereus and B. thuringiensis . 相似文献
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Glucanase-treatment of yeast cells was shown to increase the glucose fermenting activity, and decrease the sucrose and maltose fermenting activity. Also, lipase–and phospholipase–treatment decreased the fermenting activity on these sugars. However, the effects on the disaccharide fermenting activity could be reversed under various growth conditions of the yeast cells.From these results, structural factors envolved in the transport of fermentable sugars into yeast cells are discussed. 相似文献
5.
Haruhide Kawabe Hiroshi Naganawa Shinichi Kondo Hamao Umezawa Susumu Mitsuhashi 《Microbiology and immunology》1978,22(9):515-521
A clinical isolate of Staphylococcus aureus resistant to gentamicin, kanamycin and 3′,4′-dideoxykanamycin B contained two enzymes capable of inactivating gentamicin, i.e., an aminoglycoside 2″-phosphotransferase and aminoglycoside acetyltransferase. 相似文献
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The degree of methylation at the c-myc proto-oncogene was found to change in human lymphoproliferative diseases, when examined using a methylation-sensitive restriction enzyme. In peripheral blood mononuclear cells (PBMC) c-myc DNA showed hypomethylation in human lymphoproliferative diseases, in comparison to normal subjects matched in age and sex. In cases of chronic lymphocytic leukemia (CLL), the change was amplified in the crisis. When the DNA was examined at the actin gene, no significant change was observed. The results suggest that the change in c-myc proto-oncogene methylation might become an important clue in understanding the relationship between levels of gene expression and methylation in human lymphoproliferative diseases. 相似文献
8.
Y Seino K Tanaka J Takeda H Takahashi T Mitani M Kurono T Kayano G Koh H Fukumoto H Yano 《FEBS letters》1987,223(1):74-76
A cDNA clone encoding the human motilin precursor was isolated from an intestinal library using synthetic oligonucleotide probes. The predicted amino acid sequence indicates that the motilin precursor consists of 115 amino acids and includes a 25-residue N-terminal signal peptide followed by the 22-amino-acid motilin sequence and a long, 68-residue C-terminal peptide. The amino acid sequence of human motilin predicted from the cDNA sequence is identical to its porcine counterpart, which has been determined by protein sequencing. Proteolytic processing of promotilin to motilin occurs at the sequence, Lys-Lys, this being the first reported instance of processing occurring at a pair of Lys residues. In other precursors it occurs at Lys-Arg, Arg-Arg, Arg, or very rarely Lys. 相似文献
9.
Susumu Honda Shigefumi Iwase Shigeo Suzuki Kazuaki Kakehi 《Analytical biochemistry》1987,160(2):455-461
A sensitive method for determination of sialic acids by monitoring the fluorescence produced with malononitrile in borate buffer has been established. Measurement of the fluorescence intensity of the reaction mixture at 430 nm with irradiation at 360 nm allowed determination of 3-60 nmol of sialic acids with high reproducibility. A few amino sugars and deoxy sugars, as well as catecholamines reacted with this reagent; however other carbohydrates, amino acids, amines, aldehydes, and carboxylic acids including alpha-keto acids, etc., showed little reactivity. This method was successfully applied to postcolumn fluorescence labeling of sialic acids in high-performance liquid chromatography. 相似文献
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