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Biomedical subjects

K Soda

Publications and source records attributed to K Soda.

At least 307 records · Page 17Linked to original sources
PubMed1981

Detection of carriers of typhoid bacilli by sewerage-tracing surveillance in Matsuyama City.

Since periodical survey of the sewage entering the sewage-farm in Matsuyama City revealed a high incidence of Salmonella typhi of different phage types, attempts were made to trace the upstream reservoir. It was found that S. typhi was drained into a particular manhole at a distance of about 5 km from the sewage-farm. Two members of two families were found to be carriers. Further investigation detected other 25 carriers. The 27 carriers were all pupils of the same primary school. Ten of them showed mild symptoms such as fever, abdominal pain and diarrhea; the remaining 17 were asymptomatic. The phage type of 24 isolates was of Vi degraded approaching phage type A [degraded Vi(A)] and that of the other three was of type 53. The results coincided with those of the isolates from sewage.

Bacteriophage Typing↗
PubMed1980

Properties of meso-alpha,epsilon-diaminopimelate D-dehydrogenase from Bacillus sphaericus.

meso-alpha,epsilon-Diaminopimelate D-dehydrogenase, which has been purified to homogeneity from the extract of Bacillus sphaericus IFO 3525, has a molecular weight of about 80,000 and consists of two subunits identical in molecular weight (approximately 40,000). The enzyme has a high substrate specificity. In addition to meso-alpha,epsilon-diaminopimelate, lanthionine is deaminated by the enzyme to a far lesser extent. NADP+ is the exclusive cofactor. The pH optima were at about 10.5 for the deamination of meso-alpha,epsilon-diaminopimelate and at 7.5 for its amination. L and D isomers of alpha,epsilon-diaminopimelate and meso-alpha,delta-diaminoadipate competitively inhibit the oxidation of meso-alpha,epsilon-diaminopimelate. Initial velocity and product inhibition studies show that the reductive amination proceeds through a sequential ordered ternary-binary mechanism. NADPH binds first to the enzyme followed by L-alpha-amino-epsilon-ketopimelate and ammonia, and the products are released in the order of meso-alpha,epsilon-diaminopimelate and NADP+. The Michaelis constants are as follows: meso-alpha,epsilon-diaminopimelate (2.5 mM), NADP+ (83 micro M), NADPH (0.2 mM), L-alpha-amino-epsilon-ketopimelate (0.24 mM), and ammonia (12.5 mM). The pro-S hydrogen at C-4 of the dihydronicotinamide ring of NADPH is transferred to the substrate; the enzyme is B-stereospecific. Fluorometric study on binding of NADPH to the enzyme revealed that the enzyme contains two coenzyme binding sites per molecule.

Amino Acid Oxidoreductases↗
PubMed1980

A novel purification procedure of L-lysine 6-aminotransferase from Flavobacterium lutescence.

A new method for the purification of L-lysine 6-aminotransferase (L-lysine: 2-oxoglutarate 6-aminotransferase, EC 2.6.1.36) was devised, in which affinity chromatography with L-lysylacetamidododecyl-Sepharose 6B, the most effective affinity adsorbent, was substituted for the heat treatment. The yield of the enzyme with the present procedure was approx. twice as high as that with the previous procedure (Soda, K. and Misono, H. (1968) Biochemistry 7, 4110-4119). The enzyme purified by this method was activated 2-fold by heat treatment (65 degrees C for 5 min). The enzyme has absorption maxima at 340 and 415 nm, derived from the bound pyridoxal 5'-phosphate, which are identical with those of the enzyme obtained with the procedure including heat treatment. These results rule out the possibility that the formation of the 340-nm pyridoxal 5'-phosphate of the enzyme is an artifact of heat treatment.

Chromatography, Affinity↗
PubMed1980

A new antitumor enzyme, L-lysine alpha-oxidase from Trichoderma viride. Purification and enzymological properties.

L-Lysine alpha-oxidase from Trichoderma viride Y244-2 has been purified to homogeneity. The enzyme shows absorption maxima at 277, 388, and 466 nm and a shoulder around 490 nm and contains 2 mol of FAD/mol of enzyme. The enzyme has a molecular weight of approximately 116,000 and consists of two subunits identical in molecular weight (about 56,000). In addition to L-lysine, L-ornithine, L-phenylalanine, L-tyrosine, L-arginine, and L-histidine are oxidized by the enzyme to a lesser extent. Several lysine analogs such as delta-hydroxylysine are oxidized efficiently. Balance studies showed that 1 mol of L-lysine is converted to an equimolar amount of alpha-keto-epsilon-aminocaproate, ammonia, and hydrogen peroxide with the consumption of 1 mol of oxygen. alpha-Keto-epsilon-aminocaproate spontaneously is dehydrated intramolecularly into delta 1-piperideine-2-carboxylate in the presence of catalase, and is oxidatively decarboxylated into delta-aminovalerate in the absence of catalase. The Michaelis constants are as follows: 0.04 mM for L-lysine, 0.44 mM for L-ornithine, 14 mM for L-phenylalanine, and 1.6 mM for oxygen with L-lysine.

Amino Acid Oxidoreductases↗
PubMed1980

Studies on the kinetics and stoichiometry of inactivation of Pseudomonas omega-amino acid:pyruvate transaminase by gabaculine.

A homogeneous pyruvate-requiring omega-amino acid transaminase from Pseudomonas species F-126 has been examined for its behavior with gamma-aminobutyrate (GABA) as omega-amino acid substrate and for its susceptibility to the cyclic dihydroaromatic GABA analogue, gabaculine, a known suicide substrate for alpha-ketoglutarate-requiring GABA transaminases (Biochemistry 16, 4604-4610, 1977). One isomer of DL-gabaculine serves as a completely efficient titrant (no product molecules released) for this omega-amino acid transaminase by the anticipated mechanism of bound pyridoxal 5'-phosphate (PLP) derivitization. Stoichiometric titration with [2-3H]gabaculine reveals full inactivation at 0.45 labels/enzyme tetramer (see below), consistent with the subsequent demonstration that there is only 0.45 PLP molecule, bound as phenylhydrazine-titratable aldehyde form, per tetramer. Spectroscopic monitoring of inactivation also agrees with formation, on full inactivation, of 0.45 mol of m-anthranilyl-PNP adduct as the species quantitatively responsible for enzyme inactivation. Incubation of enzyme with excess PLP at 60 degrees C allows loading of enzyme with coenzyme to an average level of approximately 1 PLP/subunit, but even in this case activity is only increased up to 1.5-fold, and 1 to 1.5 molecules of gabaculine/tetramer cause complete inactivation. These data may indicate negative cooperativity between subunits.

Cyclohexanecarboxylic Acids↗
PubMed1980

L-Lysine: 2-oxoglutarate 6-aminotransferase. Subunit structure composed of non-identical polypeptides and pyridoxal 5'-phosphate-binding subunit.

L-Lysine:2-oxoglutarate 6-aminotransferase from Flavobacterium lutescence (= Achromobacter liquidum) has been shown to be composed of one each of four non-identical subunits, A, B1, B2, and C. The subunits were isolated by gel filtration, and DEAE-cellulose chromatography in the presence of 8 M urea. Their molecular weights were determined by ultracentrifugation, gel electrophoresis and gel filtration: subunit A 24,000; B1 28,000; B2 28,000; C 45,000. These subunits were all different in amino acid composition. Of the two molecules of bound pyridoxal 5'-phosphate, the one which absorbs at 415 nm is bound to subunit B2 and participates in the catalytic action of the enzyme.

Amino Acids↗
PubMed1980

Age-related symtomatology of ECHO 11 virus infection in children.

One hundred two children with ECHO 11 virus infection were analyzed as to symptomatology, which was related to the age of the patients. Neonates manifested an undifferentiated febrile illness in most cases. The symptomatology of older infants and toddlers was different from that of newborns with respect to the presence of discernible pharyngitis in two thirds of the cases. An exaggerated febrile response complicated by convulsions or gastrointestinal symptoms was another characteristic feature of this age group. A characteristic manifestation of children more than 3 years old was pharyngitis which included minute vesicular lesions or exudative ulcers around the fauces.

Age Factors↗
PubMed1979

Suicide inactivation of bacterial cystathionine gamma-synthase and methionine gamma-lyase during processing of L-propargylglycine.

L-Propargylglycine, a naturally occurring gamma, delta-acetylenic alpha-amino acid, induces mechanism-based inactivation of two pyridoxal phosphate dependent enzymes of methionine metabolism: (1) cystathionine gamma-synthease, which catalyzes a gamma-replacement reaction in methionine biosynthesis, and (2) methionine gamma-lyase, which catalyzes a gamma-elimination reaction in methionine breakdown. Biphasic pseudo-first-order inactivation kinetics were observed for both enzymes. Complete inactivation is achieved with a minimum molar ratio ([propargylglycine]/[enzyme monomer]) of 4:1 for cystathionine gamma-synthase and of 8:1 for methionine gamma-lyase, consistent with a small number of turnovers per inactivation event. Partitioning ratios were determined directly from observed primary kinetic isotope effects. [alpha-2H]Propargylglycine displays kH/kD values of about 3 on inactivation half-times. [alpha-3H]-Propargylglycine gives release of tritium to solvent nominally stoichiometric with inactivation but, on correction for the calculated tritium isotope discrimination, partition ratios of four and six turnovers per monomer inactivated are indicated for cystathionine gamma-synthase and methionine gamma-lyase, respectively. The inactivation stoichiometry, using [alpha-14C]-propargylglycine, is four labels per tetramer of cystathionine gamma-synthase but usually only two labels per tetramer of methionine gamma-lyase (half-of-the-sites reactivity). Two-dimensional urea isoelectrofocusing/NaDodSO4 electrophoresis suggests (1) that both native enzymes are alpha 2 beta 2 tetramers where the subunits are distinguishable by charge but not by size and (2) that, while each subunit of a cystathionine gamma-synthase tetramer becomes modified by propargylglycine, only one alpha and one beta subunit may be labeled in an inactive alpha 2 beta 2 tetramer of methionine gamma-lyase. Steady-state spectroscopic analyses during inactivation indicated that modified cystathionine gamma-synthase may reprotonate C2 of the enzyme--inactivator adduct, so that the cofactor is still in the pyridoxaldimine oxidation state. Fully inactivated methionine gamma-lyase has lambda max values at 460 and 495 nm, which may represent conjugated pyridoximine paraquinoid that does not reprotonate at C2 of the bound adduct. Either species could arise from Michael-type addition of an enzymic nucleophile to an electrophilic 3,4-allenic paraquinoid intermediate, generated initially by propargylic rearrangement upon a 4,5-acetylenic pyridoximine structure, as originally proposed for propargylglycine inactivation of gamma-cystathionase [Abeles, R., & Walsh, C. (1973) J. Am. Chem. Soc. 95, 6124]. It is reasonable that cystathionine gamma-synthase is the major in vivo target for this natural acetylenic toxin, the growth-inhibitory effects of which are reversed by methionine.

Alkynes↗
PubMed1979

Catalytic action of L-methionine gamma-lyase on selenomethionine and selenols.

We examined the catalytic action of L-methionine gamma-lyase (EC 4.4.1.11) on selenomethionine (2-amino-4-(methylseleno)butyric acid), methaneselenol, l-hexaneselenol, and benzeneselenol. The enzyme catalyzes alpha, gamma-elimination of selenomethionine to yield alpha-letobutyrate, ammonia, and methaneselenol, and also its gamma-replacement reaction with various thiols to produce S-substituted homocysteines. Selenomethionine is an even better substrate than methionine in alpha, gamma-elimination but is less effective in gamma-replacement. In addition, L-methionine gamma-lyase catalyzes gamma-replacement reaction of methionine and its derivatives with selenols to form the corresponding Se-substituted selenohomocysteines, although selenols are less efficient substituent donors than thiols. This is the first proven mechanism for the incorporation of selenium atom into amino acids.

Benzene Derivatives↗
PubMed1979

Purification and properties of pig liver kynureninase.

Kynureninase [L-kynurenine hydrolase, EC 3.7.1.3] was purified from pig liver by a procedure including DEAE-cellulose chromatography, hydroxyapatite chromatography, ammonium sulfate fractionation, DEAE-Bio Gel chromatography, Sephacryl S-200 gel filtration, kynurenine-Sepharose affinity chromatography, and Sephadex G-200 gel filtration. The enzyme was found to be homogeneous by the criterion of disc-gel electrophoresis. The enzyme has a molecular weight of about 100,000 and exhibits absorption maxima at 280 and 420 nm. The optimum pH and the isoelectric point of the enzyme are 8.5 and 5.0, respectively. The Michaelis constants were determined to be as follows: L-kynurenine, 7.7 X 10(-4) M; L-3-hydroxykynurenine, 1.3 X 10(-5) M; and pyridoxal 5'-phosphate, 1.8 X 10(-6) M. L-3-Hydroxykynurenine is hydrolyzed more rapidly than L-kynurenine; the liver enzyme can be regarded as a 3-hydroxy-kynureninase.

Animals↗