The structures of allosamidin (1) and methylallosamidin (2), novel insect chitinase inhibitors, were elucidated as 1 and 2 by acid hydrolysis experiments and analyses of 2d-NMR spectra. They are unique basic pseudotrisaccharides consisting of 2-acetamido-2-deoxy-d-allose (N-acetyl-d- allosamine) and a novel aminocyclitol derivative (3), termed allosamizoline. 相似文献
Oxidation of methyl trimethyl glucopyranosides which were obtained by methanolysis of permethylated cellulose, laminarin, and dextran, was performed with dimethyl sulfoxide (DMSO)-phosphorus pentoxide to afford the corresponding ulose derivatives, methyl 2,3,6-tri-O-methyl-d-xylo-hexopyranosid-4-ulose, methyl 2,4,6-tri-O-methyl-d-ribo-hexopyranosid-3-ulose, and methyl 2,3,4-tri-O-methyl-d-gluco-hexodialdo-l,5-pyranoside, respectively, in good or moderate yields. As a new type of derivatives for the linkage analysis of polysaccharides the chromatographic and spectrometric properties of 2,4-dinitrophenylhydrazone of the ulose derivatives were investigated. 相似文献
The 1C conformation was estimated for α-d-galactopyranosiduronic acid moiety of pectic acid in the permethylated derivative dissolved in 1 n NaOD-D2O and in the peracetylated derivative dissolved in dimethyl sulfoxide-d6, and the C1 conformation was estimated for some derivatives of d-galactopyranuronic acid in chloroform-d by NMR spectroscopy.
Random conformation of the whole macromolecule was estimated for pectic acid in water on the basis of no appearance of any induced Cotton effects in the 200 ~ 700 mμ region in the ORD spectra of pectic acid-anionic dye complexes.
The conformation was supported by the fact that the rate of periodate oxidation of pectic acid at 5° was slightly decreased in comparison with that of amylase in 7 m urea solution.
In bacteriophage ?X174 infection, the net synthesis of replicative form DNA ceased between 15 and 20 min after infection. When 30 μg of chloramphenicol/ml was added, net RF synthesis, however, continued beyond the normal time and level of turn-off. Experiments with ?X174 mutants unable to synthesize single-stranded DNA showed that a protein synthesis was required for the cessation of net RF synthesis and the protein was synthesized between 10 and 15 min after infection. 相似文献
Reduction of methyl 4,6-O-benzylidene-α- and β-d-glycopyranosidulose derivatives with sodium borohydride was carried out. From the yield of the axial and equatorial epimers, a possible mechanism of the borohydride reduction and factors determining the directions of the reagent’s attack to a carbonyl group are discussed. 相似文献
A new procedure which involves 1-trichloroacetyl sugars as the starting material has been developed for the synthesis of purine nucleosides. 7-β-d-Glucopyranosyl-, 7-β-d-xylopyranosyl-, 7-β-d-ribopyranosyl-theophylline, 9-(tetra-O-acetyl-β-d-glucopyranosyl)-2,6,8-trichloropurine and 9-β-d-glucopyranosyl adenine were prepared in good yields by the reaction in fusion of purine bases with 1-trichloroacetyl sugars, using zinc chloride, p-toluenesulfonic acid, or ethyl polyphosphate as catalyst. 9-d-Ribofuranosyl adenine was also prepared by the same procedures, although the anomeric configuration of the compound is not yet definite. The effect of catalysts on the yields of purine nucleosides is discussed. 相似文献
The egg white, thick and thin fractions, was solubilized in 1.0% SDS solution by vigorous mixing and subjected to gel filtration on a Sepharose 4B column, eluted with 1.0% SDS. The isolated thick and thin ovomucins were found by analytical disc electrophoresis to be free from contamination with lysozyme.
In the velocity sedimentation the two ovomucin fractions behave similarly, both comprising at least two components with sedimentation coefficients 35 S and 30 S.
The chemical compositions of the two ovomucin fractions showed only notable difference in that the carbohydrate content of the thick white ovomucin was somewhat higher than that of the thin white ovomucin. The amino acid profiles of the two fractions were similar.
1. Aminoacyl tRNA synthetase was extracted from the silkgland of silkworm (Bombyxmori Linné) and fractionated on a DEAE-cellulose column. Activities were estimated by ATP-PPi exchange reaction as well as glycyl tRNA formation.2. Two peaks, A and B, having ATP-PPi exchange activity were found in the separated fractions, respectively. There was also observed a marked difference between the both peaks with respect to the pH optimum and activity dependence on MgCl2 concentration.3. Peak A showed no activity of glycyl tRNA formation. Only a part of peak B coincided with the activity of glycyl tRNA formation. The activities of both the ATP-PPi exchange reaction and glycyl tRNA formation were found to be dependent on MgCl2 concentration, and the optimum concentration was different between two peaks.4. It also seemed to exist two peaks of activities, a and b, in glycyl tRNA formation which could be separated with a DEAE-cellulose column. 相似文献