Effect of Al2O3 or MgO on liquidus line in the FeOX corner of FeOX-SiO2-CaO system at 1523 K under various oxygen partial pressures

The liquidus line in the FeO corner of FeO SiO - CaO system and the effect by adding Al O or MgO to this plain system on the liquidus line were experimentally investigated at 1523 K in a wide range of oxygen partial pressure between about 10 and about 10 atm and for given (mass% CaO/mass% SiO / ratios in the system between 0 and about 1. It was found for the plain system that the liquidus line remarkably shifted toward the low FeO -content region when the partial pressure of oxygen was increased from 10 to 10 atm. It was clarified that the addition of Al O made the homogeneous region wide only in a strongly reducing atmosphere while the addition of MgO made the homogeneous liquid region remarkably narrow at all the oxygen partial pressures and all the (mass% CaO/mass% SiO / ratios investigated in the study

Enhancement or Suppression of ACE Inhibitory Activity by a Mixture of Tea and Foods for Specified Health Uses (FOSHU) That Are Marketed as “Support for Normal Blood Pressure”

The ACE inhibitory activities of mixtures of FOSHUs (Healthya, Goma-Mugicha, Lapis Support and Ameal) were examined in order to identify any antihypertensive interactions. Among combinations of Healthya with other samples that contain active peptides, only that with Ameal was found to have no inhibitory activity. Enhanced activity was observed in 2 other mixtures. The activity of a mixture of tea polyphenols and the whey component extracted from an Ameal solution was significantly decreased, thus demonstrating that whey protein lowered the ACE inhibitory activity of Healthya. Although oral administration of tea polyphenols alone significantly decreased SBP in SHR at 2 and 4 hr, combined administration with Ameal failed to decrease SBP at the same time points. In conclusion, the simultaneous intake of tea and FOSHUs that contain active peptides might affect daily self-antihypertensive management via enhancement or suppression of ACE inhibitory activity

Essential histidine residue in 3-ketosteroid-Δ1-dehydrogenase

金沢大学自然科学研究科　　金沢大学理工研究域自然システム学系The variation with pH of kinetic parameters was examined for 3-ketosteroid-Δ1-dehydrogenase from Nocardia corallina. The V(max)/K(m) profile for 4-androstenedione indicates that activity is lost upon protonation of a cationic acid-type group with a pK value of 7.7. The enzyme was inactivated by diethylpyrocarbonate at pH 7.4 and the inactivation was substantially prevented by androstadienedione. Analyses of reactivation with neutral hydroxylamine, pH variation, and spectral changes of the inactivated enzyme revealed that the inactivation arises from modification of a histidine residue. Studies with [14C]diethylpyrocarbonate provided Support for the idea that the 1-2 essential histidine residues are essential for the catalytic activity of the enzyme. Dye-sensitized photooxidation led to 50% inactivation of the enzyme with the decomposition of two histidine residues. This inactivation was also prevented by androstadienedione. Dancyl chloride caused a loss of the enzyme activity. Modifiers of glutamic acid, aspartic acid, cysteine, and lysine did not affect the enzyme activity. Butanedione and phenylglyoxal in the presence of borate rapidly inactivated the enzyme, indicating that arginine residues also have a crucial function in the active site. The data described support the previously proposed mechanism of β-oxidation of 3-ketosteroid

Steroid transhydrogenase activity of 3-ketosteroid-Δ1-dehydrogenase from Nocardia corallina

金沢大学自然科学研究科　　金沢大学理工研究域自然システム学系3-Ketosteroid-Δ1-dehydrogenase from Nocardia corallina catalyzes transhydrogenation of 3-keto-4-ene-steroid to 3-keto-1,4-diene-steroid e.g., progesterone to 1,4-androstadiene-3,17-dione. The reaction proceeded linearly at first and then soon slowed down owing to equilibration. The turnover number of this reaction was of the same magnitude as that of the dehydrogenation of 3-keto-4-ene-steroid. The pH optimum was 8.4, which is lower than that of the dehydrogenase reaction. The enzyme has a wide specificity for hydrogen acceptor steroids. The K(m)\u27 and K(max)\u27 values for these steroids and the values of the corresponding 3-keto-4-ene-steroids were compared. Kinetic studies of the steroid transhydrogenase reaction demonstrated a typical ping-pong mechanism. The enzyme oxidized 1,2-tritiated progesterone and transferred the tritium atoms to the reaction product, 4-androstene-3,17-dione, and water. Transhydrogenation in D2O resulted in the incorporation of a deuterium atom into the C2-position of 4-androstene-3,17-dione. The results indicate that the enzyme catalyzes C1,C2-trans axial abstraction of hydrogen atoms from progesterone, transfer of the 1α-hydrogen to the C1-position of 1,4-androstadiene-3,17-dione and release of the 2β-hydrogen to water. Reaction schemes based on the experimental results are proposed. The enzyme also catalyzes the reduction of 3-keto-1,4-diene-steroids with reduced benzoyl viologen