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Biomedical subjects

Y Tanigawa

Publications and source records attributed to Y Tanigawa.

At least 73 records · Page 4Linked to original sources
PubMed1981

Theophylline reduces poly (ADP-ribose) synthetase from chick embryo liver nuclei.

The effect of theophylline on poly(ADP-ribosyl)ation was investigated. The poly(ADP-ribose) synthetase activity in vitro was markedly reduced in the liver nuclei prepared from theophylline-treated chick embryo. This reduction was not due to the enzyme inhibition by theophylline contamination in the nuclear fraction. The hydroxyapatite column chromatographic analysis of [3H]adenosine-labelled poly(ADP-ribose)molecules formed in vivo revealed that the in vivo formation of poly(ADP-ribose)molecules was also decreased by theophylline administration. The theophylline-induced reduction of poly(ADP-ribose) synthesis was not due to either low NAD levels or to a decrease in the chain length of the poly(ADP-ribose) molecule, rather this reduction was derived from a decrease in the number of poly(ADP-ribose) molecule. Possible mechanisms related to reduction of poly(ADP-ribose) synthesis in vivo are discussed.

Animals↗
PubMed1981

Effect of polyamines on purified poly(ADP-ribose) synthetase from rat liver nuclei.

Using the purified enzyme system, we investigated the spermine-induced stimulation of poly(ADP-ribose) formation. In the presence of 2 microgram DNA and 10 mM Mg2+ in a reaction mixture of 0.2 ml, the optimal concentrations of spermine, spermidine and putrescine were 10, 12.5 and 35 mM, respectively. With the omission of Mg2+, there was an increase in optimal concentrations of polyamines without changes in the rate of poly(ADP-ribose) formation. The concentrations of spermine required for maximum synthesis of poly(ADP-ribose) were increased in proportion to the increase in the amount of DNA. Kinetic analysis of poly(ADP-ribose) formation showed a decrease in Km values for NAD with the addition of spermine. The possible relationship of polyions with regard to DNA, spermine and histone in the purified enzyme system was discussed.

Animals↗
PubMed1980

Effect of polyamines on ADP-ribosylation by chick-embryo-liver nuclei.

Effects of polyamines on poly(ADP-ribose) formation and DNA synthesis in the chick-embryo-liver nuclei were investigated. When 14-day chick-embryo-liver nuclei were incubated with [3H]NAD in the presence of 1 mM spermine, 2.5 mM spermidine, or 3.5 mM putrescine, a 9-fold increase in poly)ADP-ribose) formation was observed. Nuclei treated with nuclease showed high poly(ADP-ribose) synthetase activity as spermine-treated nuclei. However, no further increase in the polymer formation by polyamines was detected in the nuclease-treated nuclei. We found that an increase in the polymer formation by spermine was the result of an increase in both chain length and chain number of the polymer at 2.3- and 6-fold, respectively. The major ADP-ribosylated proteins were determined as two non-histone proteins of Mr 130 000 and 70 000. The experiment of DNA synthesis with nuclei ADP-ribosylated in the presence of spermine showed a 7-fold increase in [3H]dTMP incorporation into the acid-inaoluble fraction. A similar stimulation was also found with nuclei treated with other polysmines, spermidine and putrescine, in the presence of NAD. These results indicate that DNA synthesis in growing tissues containing polyamines at high levels, such as is the case with tumors and the fetus, is stimulated by polyamine-mediated ADP-ribosylation of the nuclear proteins.

Animals↗
PubMed1978

Tyrosine aminotransferase from chick liver. Heat activation and cold inactivation of the enzyme.

The reversible heat activation and cold inactivation of tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) of chick liver were investigated. When the enzyme obtained by gel filtration was preincubated at 37 degrees C for 10 min with 50 micrometer pyridoxal 5'-phosphate (pyridoxal-5'-P), a 7-fold increase in enzyme activity was detected. When the preincubated enzyme was cooled to 0 degrees C, it lost its activity. Furthermore, the dramatic cyclical changes in enzyme activity occurred by sequential heating at 37 degrees C and cooling to 0 degrees C of the enzyme, in the presence of pyridoxal-5'-P, over shorter periods of time without loss of enzyme activity. However, when alpha-ketoglutarate was added to the enzyme during cold exposure, no further decrease in activity was observed. This protective effect was seen at a concentration of 5 muM.

Animals↗
PubMed1978

Ca2+/protein modulator-dependent and -independent cyclic GMP phosphodiesterase from hog heart.

Ca2+/protein modulator-dependent and -independent guanosine 3':5'-monophosphate (cGMP) phosphodiesterases were separated from hog heart. The protein modulator-free Ca2+/protein modulator-dependent enzyme was partially purified by repeated DEAE-cellulose column chromatography and heat treatment. The final preparation of this enzyme showed no significant basal activity under the standard assay conditions. Lineweaver-Burk plots of the Ca2+/protein modulator-dependent enzyme activity indicated the presence of only a single kinetic form of the enzyme with Km=2.0 X 10(-6) M for for cGMP, whereas the plots for the independent enzyme were anomalous, showing both high and low K m values for cGMP. The Ca2+/protein modulator-dependent enzyme proved relatively stable at 48 degrees C for 1 h, but the independent form lost its activity under the same conditions. Furthermore, 50% inhibition of the dependent enzyme activity, but only 10% inhibition of the independent enzyme activity, was observed with 0.1 mM adenosine 3':5'-monophosphate (cAMP) when 1 muM cGMP was employed as a substrate.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1978

Possible participation of glucocorticoid in elevation of 3',5'-cyclic AMP levels through inhibition of cyclic AMP phosphodiesterase.

Administration of prednisolone and cholate to rats elevated levels of cAMP (adenosine 3',5'-cyclic monophosphate) by 1.5- to 2.0-fold. Compounds such as prednisolone, hydrocortisone, cholate, and deoxycholate were found to be potent inhibitors of partially purified cAMP phosphodiesterase prepared from rat liver. Kinetic analysis showed that the prednisolone inhibition was noncompetitive with a Ki of 8.9 x 10(-4) M. These results suggest that in addition to increasing DNA-dependent RNA polymerase activity in vivo, a large application of glucocorticoid may incur elevation of intracellular cAMP levels.

3',5'-Cyclic-AMP Phosphodiesterases↗