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K Kobashi

Publications and source records attributed to K Kobashi.

At least 73 records · Page 4Linked to original sources
PubMed1992

Urethanase in rat tissues.

Urethane-hydrolyzing activity (urethanase) was found in the homogenates of liver, kidney, and lung of rats. The activity was significantly higher at acidic condition (pH 5.0) than that at neutral condition (pH 7.0) in every case. The highest activity among them was observed in a kidney homogenate preparation. The activities increased slightly with treatment by Triton X-100. Intracellular distribution of urethanase in rat kidney was examined and found that the enzyme activity located mainly in the lysosomal fraction. The optimal pH was found to be 5.0. The enzyme activity was strongly inhibited by EDTA, whose 50% inhibitory concentration was 7.4 x 10(-7) M. Complete loss of the enzyme activity by the addition of EDTA was fully recovered by the addition of Zn2+, which suggested that urethanase belongs to the category of Zn enzyme.

Amidohydrolases↗
PubMed1992

Purification and characterization of novel sulfotransferase obtained from Klebsiella K-36, an intestinal bacterium of rat.

A novel type of sulfotransferase was purified from Klebsiella K-36, an intestinal bacterium of rat. The enzyme (M(r) 160,000) is composed of two subunits (M(r) 73,000) with pI and optimal pH values of 5.3 and 10-10.5, respectively. The apparent Km for PNS (p-nitrophenyl sulfate) using phenol as an acceptor and that for phenol using PNS as a donor substrate were determined to be 0.11 and 0.66 mM, respectively. The enzyme is activated by magnesium ion and inhibited by EDTA.

Animals↗
PubMed1992

Purification and characterization of a peptide essential for formation of streptolysin S by Streptococcus pyogenes.

Peptides in a pronase digest of bovine serum albumin were required for streptolysin S formation by Streptococcus pyogenes besides maltose and a carrier (the oligonucleotide fraction obtained by treatment of Saccharomyces cerevisiae RNA with RNase A). A peptide essential for streptolysin S formation was purified to homogeneity from a pronase digest of bovine serum albumin by Sephadex G-25 column chromatography, and anion-exchange, reverse-phase, and gel filtration high-performance liquid chromatography. The purified peptide was divided into more than two peptides by HCOOOH oxidation and was composed of four residues of cysteine, three of leucine, and one each of aspartic acid and glutamic acid. Leucine and cysteine were detected as amino-terminal residues, and leucine and glutamic acid were detected as carboxyl-terminal residues, suggesting that two or three peptides are linked by a disulfide bond(s). A disulfide bond structure in the peptide seemed to be required for streptolysin S formation.

Amino Acid Sequence↗
PubMed1992

Sulfation of phenolic antibiotics by sulfotransferase obtained from a human intestinal bacterium.

Novel sulfotransferase which was isolated from Eubacterium A-44, a human intestinal bacterium, sulfated phenolic antibiotics, such as amoxicillin, ceaodroxil and cefoperazone. The Km values of sulfotransferase for these antibiotics were 6.9, 4.3 and 22.2 mM, respectively. The Vmax values were 8.3, 3.3 and 1.6 mumol/min/mg protein. The optimal pH of the enzyme was 9.0, a weakly alkaline region. The antibacterial activity of amoxicillin was not altered by enzymic sulfation of the phenolic hydroxyl group.

Animals↗
PubMed1992

Inhibitory effects of glycyrrhetic acid and its related compounds on 3 alpha-hydroxysteroid dehydrogenase of rat liver cytosol.

Glycyrrhetic acid (GA), aglycone of glycyrrhizin (GL), inhibited potently (I50 = 7 x 10(-6) M) and non-competitively the activity of NAD(P)+-linked 3 alpha-hydroxysteroid dehydrogenase of rat liver cytosol. The inhibition was slightly weaker than that of indomethacin, a potent anti-inflammatory agent, but stronger than that of dexamethasone, another anti-inflammatory agent. GL, GA monoglucuronide, and 3-epi-glycyrrhetic acid also inhibited this enzyme activity, but did so less effectively (I50 = 5-8 x 10(-5) M). Carbenoxolone (GA 3-hemisuccinate) and 3-keto-glycyrrhetic acid showed potent inhibitory effects similar to GA, and 18 alpha-GA showed the most powerful inhibition of the activity.

3-Hydroxysteroid Dehydrogenases↗
PubMed1992

pH-inducible beta-glucosidase and beta-glucuronidase of intestinal bacteria.

beta-Glucosidase and beta-glucuronidase of human and rat fecal bacteria were induced by cultivation in alkaline media although their growths were not affected. When a bacterium isolated from human feces producing each enzyme was cultured in a medium at pH 5 for 12-15 h and then adjusted to pH 8, beta-glucosidase and beta-glucuronidase were induced 9.2-fold and 11.5-fold, respectively.

Animals↗
PubMed1992

Inhibition of urease activity by dipeptidyl hydroxamic acids.

A series of dipeptidyl hydroxamic acids (H-X-Gly-NHOH: X = amino acid residues) was synthesized, and the inhibitory activity against Jack bean and Proteus mirabilis ureases [EC 3.5.1.5] was examined. A number of H-X-Gly-NHOH inhibited Jack bean urease with an I50 of the order of 10(-6) M and inhibited Proteus mirabilis urease with an I50 of the order of 10(-5) M. The inhibition against Jack bean urease was more potent than that with the corresponding aminoacyl hydroxamic acids (H-X-NHOH).

Dipeptides↗
PubMed1992

Inhibitory effects of glycyrrhetic acid derivatives on 11 beta- and 3 alpha-hydroxysteroid dehydrogenases of rat liver.

Glycyrrhetic acid (GA), an aglycone of glycyrrhizin (GL), is a potent inhibitor of 11 beta- and 3 alpha-hydroxysteroid dehydrogenases. 11 beta-Hydroxysteroid dehydrogenase activity of rat liver microsomes was potently inhibited by GA, 3-deoxyglycyrrhetic acid (3-deoxyGA), 3-ketoglycyrrhetic acid (3-ketoGA), 3-epiglycyrrhetic acid (3-epiGA) and 11-deoxoglycyrrhetic acid (11-deoxoGA), with I50 values of 2-4 x 10(-7) M. However, 18 alpha-stereoisomers (I50 = 3-7 x 10(-6) M) of GA, 3-deoxyGA and 11-deoxoGA were one tenth less inhibitory on the enzyme activity than the corresponding 18 beta-isomers. On the other hand, 18 alpha-stereoisomers of GA, 3-deoxyGA and 11-deoxoGA inhibited 3 alpha-hydroxysteroid dehydrogenase activity of rat liver cytosol more potently than the corresponding 18 beta-isomers. I50 values of 18 alpha- and 18 beta-isomers were 2 and 7 x 10(-6) M, respectively, in the case of GA, 8 and 20 x 10(-6) M in 3-deoxyGA, 3 and 20 x 10(-6) M in 11-deoxoGA. These results indicate that the 18 beta-conformation of oleanane is important for the inhibition of 11 beta-hydroxysteroid dehydrogenase but on the contrary the 18 alpha-conformation is important for the inhibition of 3 alpha-hydroxysteroid dehydrogenase.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1992

The role of intestinal bacteria in the transformation of sodium picosulfate.

Sodium picosulfate, a laxative, was biotransformed to 4,4'-dihydroxydiphenyl-(2 pyridyl)-methane by intestinal flora that produced a novel sulfotransferase (not sulfatase). The biotransformation was activated by adding phenolic compounds such as phenol, acetaminophen and flavonoids. The enzyme activity related to this biotransformation was the highest in the contents of the caecum region of the intestine. The enzyme activity was 3.0 mumole/hr/g wet feces in humans and 0.75 in rats (pH 8.0). The optimal pH was 9.0.

Acetaminophen↗
PubMed1992

[Prophylactic intravesical instillation therapy in patients with superficial bladder cancer--results of a randomized prospective study].

A randomized prospective study was conducted for the purpose of investigating the efficacy of intravesical chemoprophylaxis of superficial bladder cancers. Eligible patients were randomized into three groups: 1) adriamycin (ADM) group; intravesical instillation with 50 mg of ADM dissolved in 100 ml physiological saline, 2) mitomycin C (MMC) group; intravesical instillation with 30 mg of MMC dissolved in 100 ml of physiological saline, 3) control group; transurethral resection or transurethral coagulation only. The characteristic features of our protocol consisted of frequent (six times) instillations of the drugs within two weeks after transurethral resection, followed by instillations on two consecutive days at four-week intervals for two years. Furthermore, large quantities (100 ml) of instillation fluid containing relatively low concentrations of the drugs (500 micrograms/ml for ADM or 300 micrograms/ml for MMC) were employed. One hundred and forty-four patients have been submitted to the study; 110 patients were fully evaluable for recurrence and 34 patients were eliminated as non-evaluable patients. The cumulative five-year non-recurrence rates of the patients with multiple tumors were 32% in the MMC group, 25% in the ADM group and 7% in the control group. The cumulative non-recurrence rates of the ADM and MMC groups were significantly higher than that of the control group. It is considered that this instillation therapy with ADM and MMC is useful for preventing the recurrence of superficial bladder cancers.

Administration, Intravesical↗
PubMed1992

[Histopathological study of metallothionein in bladder cancer and renal cell carcinoma].

Metallothionein (MT) is a low molecular-metal binding protein with multiple biological functions. Recently, MT has been implicated as a factor involved in resistance to anticancer drugs, which presumably inactivates anticancer drugs, including cisplatin, and doxorubicin. In this report, we investigated the relationship of MT expression with the clinical features in bladder cancer and renal cell carcinoma. In 35 cases of bladder cancer, 10 cases of renal cell carcinoma and 3 cases of normal mucosa of bladder, the expression of MT was immunohistologically examined by avidinebiotin-peroxidase (ABC) staining of paraffin-embedded tissue specimens with anti-MT antibody. Intense MT expression was noted in all cases of normal mucosa of bladder. MT was detected in 10 of 35 cases of bladder cancer, with the incidence of MT expression being significantly higher increases with lower pathological tumor grade. MT was detected in 8 of 10 cases of renal cell carcinoma, and all of the their normal renal tubules showed more intense staining. A number of hypotheses can be proposed from these observations. First, our observation of decreased MT expression in poorly differentiated carcinomas, which are the more proliferating tumors, this suggests correlation of MT expression with proliferative status of cancer. Second, the higher incidence of MT expression in renal cell carcinoma than in bladder cancer may suggest that it is a factor responsible for the lower efficacy of chemo-therapy in renal cell carcinoma than in bladder cancer.

Aged↗
PubMed1992

Relationship between substrate activity and pKa value of phenols on sulfotransferase from Eubacterium A-44.

The relationship between the kinetics of the enzyme activity and the structural features of phenolic donor and of acceptor substrates was investigated with a sulfotransferase from Eubacterium A-44, a human intestinal bacterium. The enzyme catalyzed the transfer of the sulfate group from the sulfate esters of phenol having a lower pKa to phenols having a higher pKa. When the Km values for acceptor substrates were measured at their optimal pH, a linear plot for log10Km versus the pKa with a slope of 0.615 was obtained. In addition, it is considered that the effect of pH on the Km values for the various acceptors is due to ionization of free enzyme. The kinetic behavior of bacterial sulfotransferase differed from that of mammalian phenol sulfotransferase.

Arylsulfotransferase↗
PubMed1991

Metabolism of glycyrrhetic acid by rat liver microsomes--III. Male-specific glycyrrhetinate dehydrogenase.

Glycyrrhetinate (GA) dehydrogenase localized in microsomes of rat liver catalyses the oxidation and reverse reduction of 18 beta-glycyrrhetic acid (GA), an aglycone of glycyrrhizin and a main component of liquorice, to 3-keto-18 beta-glycyrrhetic acid (3-ketoGA). The enzyme activity was detected in microsomes of adult males, but not in those of adult females. It was not observed in infant males but appeared 6 weeks after birth, increased gradually and reached the maximum level at 12 weeks after birth, whereas it was not detected in the hepatic microsomes of females of any age. The administration of estradiol valerate to intact adult males decreased GA dehydrogenase activity remarkably. Castration of male rats also caused a marked reduction of the activity, but the administration of testosterone proprionate to these rats restored it to close to the normal level. On the other hand, ovariectomy of female rats did not bring the activity into existence, but the injection of testosterone proprionate to the ovariectomized rats brought it into a slight existence, in spite of no appearance of the activity by the treatment of testosterone proprionate to intact adult females. The sex-related difference in the activity in adults was eliminated by hypophysectomy of male and female rats, their microsomal activities after the operation being the same, 20-40% of the activity in intact males. Moreover, the administration of estradiol valerate to the hypophysectomized rats did not affect the activity. These results indicate that GA dehydrogenase is male-specific and regulated by sex-hormones through the pituitary.

3-Hydroxysteroid Dehydrogenases↗
PubMed1991

Formation of nitrogen-containing metabolites from geniposide and gardenoside by human intestinal bacteria.

During the course of our studies on the metabolism of iridoid glycosides by human intestinal bacteria, we found that geniposide (1) and gardenoside (4) were transformed to new nitrogen-containing compounds, genipinine (3) and gardenine (6), respectively, along with the known aglycones. Although the amounts of new metabolites were somewhat lower than those of the aglycones, they were quantitatively analyzed by means of liquid chromatography/mass spectrometry (LC/MS). Of 25 strains of human intestinal bacteria, Peptostreptococcus anaerobius, Klebsiella pneumoniae, Fusobacterium nucleatum, and Bacteroides fragilis ssp. thetaotus produced appreciable amounts of 3, while a bacterial mixture of human feces produced 10 times or more higher amounts of 3, as compared to the individual strains.

Bacteria↗
PubMed1991

Enzymatic sulfation of polyphenols related to tannins by arylsulfotransferase.

This report discusses a novel type of arylsulfotransferase (AST) which was derived from human intestinal bacterium sulfated polyphenolic compounds when p-nitrophenyl sulfate (PNS) was taken as a donor substrate. (+)-Catechin, (+/-)-catechin, (-)-epicatechin and (-)-epicatechin gallate were better substrates than tyramine. (-)-Epigallocatechin and (-)-epigallocatechin gallate were slightly worse substrates than tyramine. Although gallic acid was a bad substrate, alkyl gallate esters were better substrates than tyramine. The degree of acceptor specificity increased in proportion to the length of the alkyl group up to the carbon number of five. Pedunculagin, geraniin and corilagin were less effective than tyramine. Rosmarinic acid and penta-O-galloyl-beta-D-glucose were similarly well sulfated. Two products, 4'-monosulfate and 4',5-disulfate of (+)-catechin, were detected at a two-fold molar excess of PNS over (+)-catechin. When (+)-catechin-4'-monosulfate as an acceptor was enzymatically sulfated with PNS as a donor, only the 4',5-disulfate was produced. Thus, arylsulfotransferase was useful for the convenient preparation of sulfate esters of polyphenols at their specific hydroxyl groups.

Arylsulfotransferase↗
PubMed1991

Effect of enzymatic sulfation on biochemical and pharmacological properties of catecholamines and tyrosine-containing peptides.

Substrate specificity of a novel sulfotransferase produced by Eubacterium A-44 isolated from human feces has been studied. Phenolic drugs, catecholamines, were good acceptors of this bacterial enzyme. With regard to dopamine, sulfation mostly occurred at the 4-aromatic hydroxy group. We also investigated the effects of enzymatic sulfation on pharmacologically active phenolic compounds. Sulfation of phenolic compounds generally led to inactivation (e.g. tyramine and Leu-enkephalin), with the exception of cholecystokinin (CCK) and some gastrointestinal peptides. Proteolytic hydrolysis in vitro did not occur at the C-terminal of the sulfated tyrosine residues of peptides such as Leu-enkephalin and kyotorphin. These results suggest that the sulfation by bacterial enzyme plays an important role in detoxification, activation and stability of phenolic compounds in the human body.

Animals↗