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Biomedical subjects

K Kiuchi

Publications and source records attributed to K Kiuchi.

112 records · Page 7Linked to original sources
PubMed1975

High-speed liquid chromatograhic separation of glycerides, fatty acids and sterols.

The high-speed liquid chromatographic separation and detection of triglycerides, diglycerides, fatty acid and sterols was carried out to permit the analyses of total lipids from soybeans and soybean food. The study was conducted with a Varian Aerograph LC 1200 liquid chromatograph equipped with a hydrogen flame ionization detector. Linear-gradient, solvent-flow programming was used. Separation of the total lipids by the gradient was achieved in 30 minutes and the column prepared for the next analysis by washing with solvents. The detector response curves for authentic compounds were linear and equivalent to within 2.3% error, based on the response to 1-monopalmitin. The minimum detectable amounts of the authentic substances were between 0.1 and 1.4mug. When a three-stranded wire was used instead of single filament wire, the sensitivity was increased by 37%.

Chromatography, High Pressure Liquid↗
PubMed1966

Specificity and mechanism of tetracycline resistance in a multiple drug resistant strain of Escherichia coli.

Izaki, Kazuo (University of Tokyo, Tokyo, Japan), Kan Kiuchi, and Kei Arima. Specificity and mechanism of tetracycline resistance in a multiple drug resistant strain of Escherichia coli. J. Bacteriol. 91:628-633. 1966.-A decrease in the uptake of tetracycline occurred concurrently with a rise in the level of resistance of a multiple drug resistant strain of Escherichia coli grown in the presence of tetracycline. Although the strain was also resistant to streptomycin and chloramphenicol, growth in the presence of these two antibiotics did not influence the uptake of tetracycline. The induction of resistance, or decreased uptake of tetracycline, was dependent on growth of the organism in the presence of the drug. Decreased uptake of tetracycline could not be induced in a sensitive strain of the same organism under conditions suitable for induction of the resistant strain. The decrease in accumulating power of the resistant organism cultured in the presence of tetracycline does not appear to be due to selection of a resistant strain from cultures containing both resistant and sensitive strains.

Chemical Phenomena↗
PubMedDate not supplied

Alteration of the substrate specificity of Aspergillus oryzae beta-galactosidase by modification with polyethylene glycol.

beta-Galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) purified from Aspergillus oryzae was modified with 2,4,6-trichloro-s-triazine derivatives of polyethylene glycol (activated BPEG) having molecular weights of 600, 1500, 2000, and 4000. Polyethylene glycol derivatives were attached to 6 of the 12 amino groups exposed on the surface of the enzyme. Upon modification, the enzymatic activity for a water-soluble substrate, o-nitrophenyl beta-D-galactopyranoside, was reduced with increasing molecular weight of the activated BPEG. On the contrary, the enzymatic activity for another substrate, 4-methylumbelliferyl beta-D-galactopyranoside, was increased upon modification. The Michaelis constants of native and modified enzymes for these two substrates were virtually the same. The effect of the modification was more marked in the enzymatic hydrolysis of the beta-galactosidic bond of amphipathic substrates. A fluorescent analog of naturally occurring galactocerebroside, 1-O-galactosyl-2-N-(1-dimethylaminonaphthalene-5-sulfonyl)-sphingosine, was hydrolyzed more rapidly by the modified enzyme than by the native one. The enzyme modified with activated BPEG of 1500 Da had the highest activity for this substrate. The beta-galactosidic bond of the terminal galactose of GM1-ganglioside (II3NeuAcGgOse4Cer, galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminosyl)-galactosyl -glucosylceramide) was cleaved by the modified but not by the native enzyme.

Aspergillus↗