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K Asaoka

Publications and source records attributed to K Asaoka.

At least 109 records · Page 6Linked to original sources
PubMed1984

Affinity purification and characterization of glutathione S-transferases from bovine liver.

Conditions have been investigated for the use of triazine dye agarose as an affinity matrix for the purification of glutathione S-transferases from bovine liver. Orange A agarose was most suitable for this purpose among various dye agaroses tested. The enzymes were adsorbed on the dye agarose column and then completely eluted with the buffer containing 1 mM reduced glutathione. Thus, a simple and rapid method for purification of bovine liver transferases was developed, which uses column chromatographies on orange A agarose followed by DEAE-Sephacel. One step of the affinity chromatography provided 40-fold purification. Upon chromatography on DEAE-Sephacel, the enzyme activity separated into two major forms (I and II), which were purified to apparent homogeneity as examined by polyacrylamide gel electrophoreses. The pI values of the two forms, I and II, were 6.7 and 6.1, respectively. The overall extents of purification of I and II were about 40-fold and 50-fold, respectively. The activities of the two major enzymes toward various substrates were roughly similar. The optimum pH values of these enzymes were 7.5 as measured with o-dinitrobenzene as a substrate. The activities were significantly inhibited by Cu2+, Hg2+, Cd2+, and Zn2+. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, both enzymes showed one band with a molecular weight of about 27,000. Both enzymes, however, were eluted as a single peak from a Sephadex G-150 column at a position corresponding to a molecular weight of about 49,000. These results show that each enzyme consists of two subunits bound to each other non-covalently. The amino acid compositions showed characteristically high contents of leucine and aspartic acid residues. Double immunodiffusion showed complete identity of the two forms reacting with both rabbit anti-enzyme sera. The two enzymes had an identical amino-terminal amino acid sequence as follows: H-Pro-Met-Ile-Leu-Gly-Tyr-Trp-Asp-Ile-Arg-Gly-Leu-Ala-His-Ala-Ile-Ser-Le u-Leu-Leu.

Amino Acids↗
PubMed1983

Purification and properties of porcine brain glutathione S-transferases.

Glutathione S-transferase was purified from porcine brain. Four enzyme fractions were obtained by column chromatography on CM-cellulose and the main enzyme fraction was purified to apparent homogeneity as judged by disc gel electrophoresis. The action spectra of these enzyme fractions toward some typical substrates were roughly similar. The optimum pH range of the purified enzyme was from 6.5 to 7.5 with o-dinitrobenzene as a substrate. The main enzyme showed a molecular weight of about 43,000 on Sephadex G-150 chromatography, and about 22,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was composed of two subunits of apparently identical molecular weight bound to each other noncovalently. The amino acid composition showed characteristic high contents of leucine and glutamic acid residues. A notable difference was observed in the lysine content as compared with that of the liver enzyme. The brain enzyme bound bilirubin less strongly than the monkey liver enzyme and human albumin. In addition, the regional and subcellular distributions of the enzyme in porcine brain was investigated with o-dinitrobenzene as a substrate. The enzyme activity was found to be distributed fairly evenly in various regions of the brain, and was especially abundant in the cytosol fraction. However, the enzyme activity was also detected considerably in the microsomal and mitochondrial fractions but not in the synaptosomal fraction.

Amino Acids↗
PubMed1983

A colorimetric assay of glutathione S-transferases using o-dinitrobenzene as a substrate.

Conditions have been examined for the use of o-dinitrobenzene as a substrate for colorimetric assay of glutathione S-transferases. Activities can be determined by measuring nitrite released enzymatically from the substrate using a diazo-coupling method with N-(1-naphthyl)ethylenediamine dihydrochloride and sulfanilamide. The assay can be done in the presence of large amounts of reduced glutathione (GSH), cysteine, and protein, and is capable of quantitating the enzyme activity in about 30 micrograms (wet weight) of monkey liver, corresponding to 0.1 microgram of purified glutathione S-transferase from the same source. This method is suitable for assaying simultaneously a large number of samples with reasonable sensitivity and speed.

Animals↗
PubMed1981

An enzymatic assay of reduced glutathione using glutathione S-aryltransferase with o-dinitrobenzene as a substrate.

A simple and sensitive enzymatic assay method for the determination of reduced glutathione (GSH) has been developed using glutathione S-aryltransferase with o-dinitrobenzene as a substrate. o-Dinitrobenzene is a good substrate for the enzyme and has low spontaneous reactivity with GSH at neutral pH. GSH can be determined by colorimetrically measuring nitrite released upon the enzymatic conjugation of GSH and o-dinitrobenzene by using a diazo-coupling method with N-(1-naphthyl)ethylenediamine dihydrochloride. This method is capable of quantitating 1 to 40 nmol of GSH, and can be applied to physiological samples containing deproteinizing reagents.

Animals↗
PubMed1981

[Studies on the mechanical properties of dental Ag-Pd-Au-Cu alloys. (Part 1) Effects of age-hardening treatment on the tensile behaviour of alloys (author's transl)].

Tensile behaviour of Ag-Pd-Au-Cu alloys depending on age-hardening was studied by the tensile test with extensometer. The fractured surface of the alloys was observed by the scanning electron microscope. Plastic deformation of alloys was changed from discontinuous yielding to parabolic strain hardening, as the size of precipitate hard particles was grown by aging. There appears to be good correlation between the tensile strength of alloys with aging and the hardness. Strain hardening parameters of the Ludwik, Swift, Voce and Hollomon empirical equations in describing the stress-strain curves were calculated by the least square method. Theoretical tensile strength which was computed from these empirical equations, was good agreement with the tensile test of alloys with aging. But, theoretical uniform elongation tended to elongate. The ratio of tensile strength to proof stress of over-aged alloys was extremely low, as compared with the other alloys. So, over-aging should be avoided to use the alloys in dentistry. If structure of the precipitate particles is controlled by aging temperature and time, the loss of ductility on age-hardening will be considerably eliminated.

Chemical Phenomena↗
PubMed1980

[Studies on the mechanical properties of a metal-ceramic restoration. (Part I) Estimation of the bond strength by pull-out test (author's transl)].

Metal-ceramic composite materials as a porcelain fused to metal restoration, have been used for biomaterials. But the chief objection, to use of these materials as restorative materials, is its lack of strength, particularly tensile and shear strength. And the materials to have strong bond strength have been studied. On the other hand, the bond strength along metal-ceramic interface have usually measured by a pull out test. At the same time, the objection of the pull out test are pointed out. So, the deformation of metal-ceramic composite materials by the pull out test were simulated to use the axi-symmetric finite element method. And shear stress distribution along the interface and the principal stress distribution in ceramic were calculated. The following results were obtained. (1) Shear stress along the interface and maximum principal stresses in ceramic and in metal decrease rapidly along the interface. (2) The stress concentration factor as the case of the alloy with high Young's modulus is smaller than that of the alloy with low Young's modulus. So, the former would be stronger about the pull out test. (3) Metal-ceramic interface length is not affected for shear stress concentration. If the specimen has more than the critical interface length, the initial crack in ceramic would be occurred at the same pull out force.

Dental Bonding↗
PubMed1977

[A study on the incidence of post-partum hypopituitarism, (Sheehan's syndrome)].

The frequency of post-partum hypopituitarism (Sheehan's syndrome) is difficult to assess. It is the purpose of this paper to ascertain the incidence of post-partum hypopituitarism in Okayama Red Cross Hospital. Out of 19,302 women who delivered at the hospital during 10 years from 1961 to 1970, we selected 1.010 women who had a blood loss of 500 ml. or more at delivery. Firstly, after having sent the selected women a questionnaire by post, we investigated whether they had Sheehan's syndrome or not from the response of the 392 women who replied to the questionnaire. Secondly, 126 of the 392 women who came to our clinic when requested were examined concerning blood picture, fasting blood glucose, and the serum levels of cholesterol, thyroxine, cortisol, GH, TSH, LH and FSH. As a control, 24 women who had had a normal delivery were examined as described above. No advanced hypopituitarism or mild hypopituitarism was found in this follow-up study. Compared with Sheehan's series in England, it was found the incidence of post-partum hypopituitarism in Okayama was presumably less than in England. Suggestions for this discrepancy are as follows: (1) competent obstetric care and a rapid blood transfusion after gross post-partum hemorrhage in Okayama Red Cross Hospital. (2) an incomplete report of the incidence of post-partum hypopituitarism due to those who did not reply to the questionnaire. (3) the rarity of the frequency of Sheehan's syndrome in Japan.

Adult↗
PubMed1977

Monkey glutathione S-aryltransferases. II. Properties of the major enzyme purified from the liver.

1. The molecular and enzymatic properties of the major component (Fraction IV) of glutathione S-aryltransferases [EC 2.5.1.13] purified from the liver of monkey (mainly rhesus monkey) have been investigated. The enzyme had a molecular weight of about 48,000 and was composed of two subunits of apparently identical molecular weight (ca. 24,000) bound to each other non-covalently. Each subunit contained one SH group. The amino acid composition showed characteristic high contents of leucine and glutamic acid residues. No amino-terminal residue was detected by the dansyl method. 2. The enzyme showed a rather broad optimum pH range from 7.5 to 9 with 1,2-dichloro-4-nitrobenzene as a substrate. It was moderately stable below 40 degrees C at pH 7.5. However, it showed an anomalous instability at pH around 4.2. It was reversibly denatured at least partially by urea or guanidine hydrochloride and irreversibly denatured by sodium dodecyl-sulfate. It was significantly inhibited by Zn2+, Cd2+, and Hg2+, and also by benzene hexachloride. It was extensively inactivated by reaction with phenylglyoxal or 2,4,6-trinitrobenzene sulfonate, whereas several SH reagents were without marked effect on the activity under the reaction conditions employed.

Amino Acids↗