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T Yagi

Publications and source records attributed to T Yagi.

At least 487 records · Page 27Linked to original sources
PubMed1991

Non-sequence databases for biological activity and physicochemical properties.

A biological activity database and a physicochemical property database are described. They are intended to complement the protein sequence database of PIR-International. The Biological Activity Database and the Physicochemical Property Database contain information regarding the biological activity and the physicochemical properties of proteins, respectively. In addition they also provide information about wild-type molecules with which information concerning variant molecules may be compared. Data on artificial variant molecules are stored in the Artificial Variant Database which is described separately.

Amino Acid Sequence↗
PubMed1991

Characterization of the half and overall reactions catalyzed by L-lysine:2-oxoglutarate 6-aminotransferase.

Significant differences were found in the reaction rate, and the substrate and reaction specificities between the half reactions and the overall reactions catalyzed by L-lysine: 2-oxoglutarate 6-aminotransferase. The half reactions between an amino donor and the enzyme-bound pyridoxal 5'-phosphate, and also between an amino acceptor and the bound pyridoxamine 5'-phosphate followed first order reaction kinetics. The extrapolated first order rate constants and dissociation constants of the substrates were determined for the half reactions: lysine, 0.87 min-1 and 5.5 mM; glutamate, 1.1 min-1 and 10.5 mM; alanine, 0.66 min-1 and 6.6 mM; 6-aminohexanoate, 0.43 min-1 and 13.3 mM; and 2-oxoglutarate, 0.33 min-1 and 2.5 mM. As compared with the values reported for the overall reactions [Soda, K., Misono, H., & Yamamoto, T. (1968) Biochemistry 7, 4102-4109], the reactivity of the inherent substrates was lower by over 4 orders in the half reaction than that in the overall reaction, and the reactivity of alanine with the bound pyridoxal 5'-phosphate was reduced to 10% of that in the overall reaction. The substrate specificity in the half reaction was much lower than that in the overall reaction, which was re-examined in a reaction system containing the same concentration of the enzyme as that for the half reactions. Lysine 6-aminotransferase catalyzes the transfer of only the terminal amino group of lysine to 2-oxoglutarate in the overall reaction. However, in the half reaction, the 2-amino group as well as the terminal one was transferred to the bound pyridoxal 5'-phosphate. The ratio of reactivity of the 2-amino group to that of the 6-amino group was considerably influenced by the pH of the reaction mixture.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1990

Expression of major histocompatibility complex class II antigens and interleukin-1 by epithelial cells of Warthin's tumor.

The immunoreactivity for class II antigens of the major histocompatibility complex and interleukin-1 (IL-1) in Warthin's tumor (WT) cells was studied. In addition to macrophages, dendritic cells, and capillary endothelia, the luminal tumor cells and some keratinocytes in the metaplastic squamous foci exhibited immunoreactivity for both class II antigens and IL-1. The distribution of the class II antigens in the luminal tumor cells was limited to their basolateral membrane. These data, together with previous findings, strongly suggest that the luminal tumor cells of WT introduce the luminal antigen to the underlying lymphoid tissue and, thus, act as an antigen-presenting cell.

Adenolymphoma↗
PubMed1990

Identification of the NADH-binding subunit of NADH-ubiquinone oxidoreductase of Paracoccus denitrificans.

The NADH dehydrogenase complex isolated from Paracoccus denitrificans is composed of approximately 10 unlike polypeptides and contains noncovalently bound FMN, non-heme iron, and acid-labile sulfide [Yagi, T. (1986) Arch. Biochem. Biophys. 250, 302-311]. When the Paracoccus NADH dehydrogenase complex was irradiated by UV light in the presence of [adenylate-32P]NAD, radioactivity was incorporated exclusively into one of three polypeptides of Mr approximately 50,000. Similar results were obtained when [adenylate-32P]NADH was used. The labeling of the Mr 50,000 polypeptide was diminished when UV irradiation of the enzyme with [adenylate-32P]NAD was performed in the presence of NADH, but not in the presence of NADP(H). The labeled polypeptide was isolated by preparative sodium dodecyl sulfate gel electrophoresis and was shown to cross-react with antiserum to the NADH-binding subunit (Mr = 51,000) of bovine NADH-ubiquinone oxidoreductase. Its amino acid composition was also very similar to that of the bovine NADH-binding subunit. These chemical and immunological results indicate that the Mr 50,000 polypeptide is an NADH-binding subunit of the Paracoccus NADH dehydrogenase complex.

Animals↗
PubMed1990

Studies on the NADH-menaquinone oxidoreductase segment of the respiratory chain in Thermus thermophilus HB-8.

Five distinct low potential iron-sulfur clusters have been identified potentiometrically in the membrane particles from Thermus thermophilus HB-8. Three of these clusters (designated as [N-1H]T, [N-2H]T, and [N-3]T) exhibit the following midpoint redox potentials and g values (Em8.0 = -274 mV, gx,y,z = 1.93, 1.94, 2.02), (Em8.0 = -304 mV, gx,y,z = 1.89, 1.95, 2.04), and (Em8.0 = -289 mV, gx,y,z = 1.80, 1.83, 2.06), respectively. These clusters, one binuclear and two tetranuclear, have been shown to be components of the energy coupled NADH-menaquinone oxidoreductase complex (NADH dh I). They are reducible by NADH in the piericidin A-inhibited aerobic membrane particles as well as in the purified NADH dh I complex. Two additional very low potential iron-sulfur clusters (one binuclear, [N-1L]T, and one tetranuclear, [N-2L]T) were observed in membrane particles. These clusters possess the following physiochemical properties (Em8.0 = -418 mV, gx,y,z = 1.93, 19.5, 2.02) and (Em8.0 = -437 mV, gx,y,z = 1.89, 1.95, 2.04), respectively. No high potential tetranuclear cluster equivalent to the mitochondrial iron-sulfur cluster [N-2]B was found in this bacterial system. In membrane particles isolated from T. thermophilus HB-8 cells, four different semiquinone species have been identified based on their redox midpoint potentials [Em9(Q/QH2) = 40, -100, -160, -300 mV] and sensitivity to the quinone analogue inhibitor, 2-heptyl-4-hydroxy quinoline-N-oxide. Of these semiquinone species the -100 mV component has been suggested to be part of the NADH dehydrogenase. Piericidin A sensitive delta psi formation has been demonstrated to be coupled to the NADH-MQ1 oxidoreductase in membrane vesicles of T. thermophilus HB-8.

Cell Membrane↗
PubMed1990

Eye movement analysis system using computerized image recognition.

A new technique for an eye movement analysis system utilizing infrared video recording and a computerized image recognition method is presented. The system consists of an infrared lighting apparatus, a very small infrared video charge-coupled device camera, a video tape recorder, an analogue-digital converter, and microcomputers. This system makes it possible to simultaneously analyze the slow-phase velocity quantitatively not only of the horizontal and vertical but also of the rotatory components of the energy-induced nystagmus. The maximum slow-phase velocity of the rotatory component of energy-induced nystagmus was found to be 4.1 degrees per second on an average in this study.

Adult↗
PubMed1990

Env-derived gp55 gene of Friend spleen focus-forming virus specifically induces neoplastic proliferation of erythroid progenitor cells.

A group of retroviruses carrying truncated viral genes has recently been suggested as the cause of new patterns of diseases. One such virus is the replication defective component of the Friend murine leukemia virus (F-MuLV) complex, called Friend spleen focus forming virus (F-SFFV). This virus induces erythroblastosis, and a virion envelope-related glycoprotein, gp55, encoded by F-SFFV has been suggested as the pathogenic gene. The role of the gp55 gene is, however, yet unclear in the apparently multistep erythroleukemogenesis. By separately producing transgenic mice harboring the whole F-SFFV DNA, the gp55 gene alone under the control of the retroviral long terminal repeat (LTR) and the gp55 gene under the control of cytoplasmic beta actin transcriptional regulatory unit, we show here that the gp55 gene is capable of inducing neoplastic proliferation of erythroid progenitor cells specifically in the absence of helper virus and other F-SFFV sequences. Under the control of the viral LTR the gp55 expression was detected only in leukemic tissues, but under the control of cytoplasmic beta-actin regulatory sequences, the gp55 was also expressed in a variety of normal tissues including preleukemic normal spleens. The development of erythroleukemia was suppressed under the genetic background of C57B1/6 mouse (resistant to F-MuLV; Fv-2rr), and required additional events even under the background of DDD mouse (susceptible to F-MuLV; Fv-2ss). The p53 and Spi-1 genes were frequently aberrant in transplanted tumors and cell lines derived from them, but were not in primary leukemic spleens.

Animals↗
PubMed1990

Induction of a variety of tumors by c-erbB2 and clonal nature of lymphomas even with the mutated gene (Val659----Glu659).

The c-erbB2 gene is expressed uniquely in fetal epithelium in vivo and has been suggested to contribute to the development and/or progression of adenocarcinomas in man. In order to assess the oncogenicity of the c-erbB2 gene in vivo, normal c-erbB2 and mutant c-erbB2 encoding glutamic acid instead of valine at position 659 within the transmembrane domain were introduced into mice under the transcriptional regulatory unit of mouse mammary tumor virus long terminal repeat (MMTV-LTR) or immunoglobulin enhancer--SV40 early gene promoter (Ig/Tp). In transgenic mice with normal c-erbB2 under MMTV-LTR, not only adenocarcinomas but also a variety of tumors including B lymphomas were induced at relatively late onset. Induction of pre-B cell lymphomas with normal c-erbB2 was also observed using the Ig/Tp regulatory unit within 6-10 months in some members of one transgenic family among seven lines established. In contrast, with the mutant c-erbB2 under the Ig/Tp regulatory unit, the lymphoma was induced neonatally in all members of four transgenic families among ten lines obtained. However, the immunoglobulin heavy chain gene rearrangement pattern indicated that even with the mutant c-erbB2 the induced lymphomas were clonal.

Adenocarcinoma↗
PubMed1990

Inhibition by capsaicin of NADH-quinone oxidoreductases is correlated with the presence of energy-coupling site 1 in various organisms.

The NADH-ubiquinone reductase activity of the respiratory chains of several organisms was inhibited by capsaicin and dihydrocapsaicin, which are the pungent principles of red pepper. This inhibition was correlated with the presence of an energy transducing site in this segment of the respiratory chain. Where the NADH-quinone oxidoreductase segment involved an energy coupling site (e.g., in Paracoccus denitrificans, Escherichia coli, and Thermus thermophilus HB-8 membranes and bovine heart mitochondria), capsaicin acted as an inhibitor of ubiquinone reduction by NADH. In contrast, where this energy coupling site was absent (e.g., in Saccharomyces cerevisiae mitochondria and Bacillus subtilis membranes), there was no inhibition of NADH-ubiquinone reductase activity by capsaicin. The capsaicin inhibition of Paracoccus membranes was reversed by washing the membranes with medium containing bovine serum albumin. In the E. coli and Paracoccus membranes and bovine submitochondrial particles, capsaicin acted as a noncompetitive inhibitor for ubiquinone-1 at lower concentrations of ubiquinone-1 (less than 20 microM) and as a competitive inhibitor at higher concentrations of ubiquinone-1 (greater than 50 microM). In addition, the concentrations of capsaicin required for 50% inhibition of NADH oxidase activity of bovine submitochondrial particles were increased when ubiquinone-10 was added to the particles. The mechanism by which capsaicin inhibits the energy-transducing NADH-quinone oxidoreductase is discussed.

Animals↗
PubMed1990

Homologous recombination at c-fyn locus of mouse embryonic stem cells with use of diphtheria toxin A-fragment gene in negative selection.

In attempting to produce a mutant mouse with embryonic stem cells, the critical step is the efficient isolation of homologous recombinants; the frequency of the homologous recombination is usually low and the potency of the cells to differentiate into germ cells is unstable in culture. Here, we report an efficacious method for such isolation in which the diphtheria toxin A-fragment gene is used to negatively select nonhomologous recombinants. In contrast to the use of the herpes simplex virus thymidine kinase gene, the selection can be made singly by the neomycin analog G418 without using a drug such as ganciclovir, a nucleoside analog. At the c-fyn locus, the diphtheria-toxin negative selection enriched the recombinants about 10-fold, and half of the cells integrating with the neomycin phosphotransferase gene were homologous recombinants.

Animals↗
PubMed1990

Distribution of aspartate aminotransferase activity in yeasts, and purification and characterization of mitochondrial and cytosolic isoenzymes from Rhodotorula minuta [corrected].

The distribution of aspartate aminotransferase activity in yeasts was determined. The number of species of the enzyme in each yeast was determined by zymogram analysis. All the yeasts, except for the genus Saccharomyces, showed two or three activity bands on a zymogram. From among the strains, Rhodotorula minuta [corrected] and Torulopsis candida were selected for examination of the existence of yeast mitochondrial isoenzymes, because these strains showed two clear activity bands on the zymogram and contained a high amount of the enzyme. Only one aspartate aminotransferase was purified from T. candida: the component in the minor band on the zymogram was not an isoenzyme of aspartate aminotransferase. On the other hand, two aspartate aminotransferases were purified to homogeneity from R. minuta [corrected]. The components in the main and minor activity bands on the zymogram were identified as the mitochondrial and cytosolic isoenzymes, respectively, in a cell-fractionation experiment. The enzymatic properties of these isoenzymes were determined. The yeast mitochondrial isoenzyme resembled the animal mitochondrial isoenzymes in molecular weight (subunits and native form), absorption spectrum, and substrate specificity. The amino acid composition was closely similar to that of pig mitochondrial isoenzyme. Rabbit antibody against the yeast mitochondrial isoenzyme, however, did not form a precipitin band with the pig mitochondrial isoenzyme.

Amino Acids↗
PubMed1990

S-class cytochromes c have a variety of folding patterns: structure of cytochrome c-553 from Desulfovibrio vulgaris determined by the multi-wavelength anomalous dispersion method.

The three-dimensional structure of cytochrome c-553 isolated from sulfate-reducing bacterium, Desulfovibrio vulgaris Miyazaki F strain, has been determined by the multi-wavelength anomalous dispersion technique with use of synchrotron radiation. The result shows that bacterial S-class cytochromes c have a variety of folding patterns. The relative location of two a-helices at amino- and carboxyl-terminals and the style of bonding to the heme group show "cytochrome c folding," but other regions of the structure are different from those of other cytochromes c previously reported. The results also give useful information about the location of sulfate-reducing bacterium on the phylogenetic tree of the bacterial cytochromes c superfamily.

Amino Acid Sequence↗
PubMed1990

Benign lymphoepithelial lesion with large cysts: case report.

A case of benign lymphoepithelial lesion with two large cysts and many foci of duct dilatation is reported. Clinical features, except for absence of dry eyes, indicated the case was Sjögren's syndrome. The cysts were found in the left parotid gland of a 60-yr-old woman and were surgically removed. The size of each cyst was 20 mm in diameter and one of them was located in the lymph node. Because of the HLA-DR expression by the epithelium, the cysts are considered to have formed as a result of duct dilatation due to autoimmune response. As for one cyst, it is also possible that the pre-existing lymphoepithelial cyst might be involved in the autoimmune phenomenon because of its relation to the lymph node.

Cysts↗
PubMed1990

Prostaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colon.

Rhein anthrone, the active metabolite of sennosides A and B, stimulated PGE2 release into the mouse colonic lumen. At 6.24 mg kg-1, it decreased net water and Na+ absorption significantly in the case of water, but could not reverse the net absorption in mouse ligated colon, although it enhanced net K+ secretion. Pretreatment with indomethacin diminished the effects of rhein anthrone except on K+ net secretion. Rhein anthrone or PGE2 markedly stimulated mucus secretion and synthesis in mouse ligated colon. The enhanced mucus secretion and synthesis induced by rhein anthrone were significantly suppressed by pretreatment with indomethacin. Our results have shown that the colonic secretion of water and electrolytes mediated by PGE2 is partly involved in the rhein anthrone-induced diarrhoea but that in mice, the mucoid diarrhoea induced by rhein anthrone results mainly from PGE2-mediated mucus synthesis and secretion in the colon.

Animals↗
PubMed1990

[Application of sensitive reverse transcriptase assay to human immunodeficiency virus (HIV) type 2].

Sensitive reverse transcriptase assay was applied to human immunodeficiency virus type 2. The kinetics of this assay, stability of the enzyme and the effect of BSA to this assay indicated that the condition of this assay should be 37 degrees C in reaction temperature. The sensitivity of this assay increased by adding more than 10 micrograms/ml of BSA. The sensitivity of this assay is at least four times more than that of CPE assay using Molt-4 cell. Other HIV-2 isolate, LAV-2 in culture medium was also detectable in this condition. Moreover reverse transcriptase inhibiting antibody that specifically inhibits HIV-2 reverse transcriptase was found by this assay.

HIV↗