The level of beta-alanine aminotransferase activity in regenerating and differentiating rat liver

beta-Alanine aminotransferase from rat liver was purified to electrophoretic homogeneity. The immunological and kinetic properties of this enzyme were similar to those of the enzyme from rat brain. However, the liver enzyme transaminates from beta-alanine to 2-oxoglutaric acid, while the brain enzyme transaminates from gamma-aminobutyric acid. beta-Alanine aminotransferase activity in regenerating rat liver was lower than that in control rat liver. Activity of this enzyme, as well as of other uracil-catabolizing enzymes (Weber, G., Queener, S.F. and Ferdinandus, A. (1970) in Advances in Enzyme Regulation (Weber, G., ed.), Vol. 9, pp. 63-95, Pergamon Press, Oxford), was low in newborn rat liver and increased about 5-fold, reaching the level observed in adult rat liver. beta-Alanine and prednisolone induced beta-alanine aminotransferase in rat liver.     

A cell-binding, immunoglobulin-like protein from human plasma. II. Cell-binding activity

Cell adhesion to plastic surfaces coated with a new high-molecular-mass immunoglobulin-like protein from normal human plasma was studied. Mouse subdermal fibroblasts, hamster kidney cells, human umbilical vein endothelial cells, and human skin fibroblasts were found to become attached to the surface, but cancer cells derived from human stomach cancer and human breast cancer did not. The appearance of the attached cells differed from that of cells attached to surfaces coated with fibronectin or concanavalin A. The cell adhesion to the surfaces coated with the protein was inhibited by goat anti-human IgM. Furthermore, the binding of the protein to the cell surfaces was demonstrated by the indirect immunofluorescence method. It is concluded that this protein is a new cell-binding protein.     

Corrosion casting method for the gross anatomy of the blood vascular system of fish

A corrosion cast of the entire blood vascular system was made by a single injection of resin from the heart of carp and a Japanese catfish. Either semipolymerized methyl methacrylate or Mercox CL with 30–50% methyl methacrylate monomer was used as the resin preparation. The latter was better for photographing. Both were polymerized by addition of 1 % benzoyl peroxide. The segmental blood vessels of carp and a catfish showed an alternating arrangement of artery and vein in successive segments with some irregularity.     

A role for the lipoxygenase pathway of arachidonic acid metabolism in glucose- and glucagon-induced insulin secretion

Although the cylo-oxygenase pathway of arachidonic acid (AA) metabolism inhibits glucose-stimulatedinsulin release throught synthesis of prostaglandins, very little attention has been given to the effects of lipoxygenase pathway products on beta cell function. We have examined the effects of two structurally-dissimilar lipoxygenase inhibitors on insulin release from mono-layer-cultured rat islet cell. Both nordihydroguaiaretic acid (NDGA, 20–50 μM) and BW755c (100–250μM) caused a dose-responsive inhibition of glucose-induced insulin release. This inhibitory effect occurred despite concomitant inhibition of prostaglandin E synthesis. Lipoxygenase inhibitors also impeded cyclic AMP accumulation. Insulin and cyclic AMP release induced by glucagon were also blunted. These studies suggest the hypothesis that AA released in or near the beta cell is metabolized to lipoxygenase product(s) which have feed-forward properties important to glucose- and glucagon-stimulated cyclic nucleotide accumulation and insulin release.     

ATP synthesis linked to light-dependent proton uptake in a red mutant strain of Halobacterium lacking bacteriorhodopsin

Intact cells of Halobacterium halobium R₁mR, a red strain deficient in bacteriorhodopsin, pumped protons only in an inward direction when illuminated, in contrast to R₁ cells which showed proton transfer in both directions. The cellular ATP level of R₁mR, as well as R₁ cells, under nitrogen, was increased upon illumination to the aerobic level. The proton uptake and ATP synthesis observed with both R₁ and R₁mR occurred even after the majority of bacteriorhodopsin (in R₁) had been bleached with NH₂OH, but they were abolished by brief heat treatment of the cells. These results suggest a mechanism common to both strains which is responsible for the observed proton uptake and ATP synthesis. When R₁mR cells were grown in the presence of nicotine, an inhibitor of carotenoid biosynthesis, both the proton uptake and ATP synthesis were completely depressed, but recovered after all-trans retinal was added externally. The action spectrum by R₁mR, NH₂OH-treated R₁, or nicotinegrown R₁mR reconstituted with retinal consistently exhibited a maximum between 580 and 600 nm. Hence the mechanism is independent of bacteriorhodopsin of the purple membrane. Instead, our results indicate the possible presence of a new chromoprotein which involves retinal as the chromophore and participates in the mechanism of cellular ATP synthesis.     

α-Hydroxylation of Fatty Acids in Brain: Characterization of Heat-Labile Factor

Abstract: The particulate fraction, heat-labile factor, heat-stable factor, and NADPH are essential for the conversion of lignoceric acid (tetracosanoic acid) to cerebronic acid (α-hydroxylignoceric acid). The heat-labile factor was extracted from calf cerebellum and partially purified in four steps: ammonium sulfate precipitation, hydroxylapatite chromatography, isoelectric focusing, and NAD-Agarose affinity chromatography. The specific activity of the heat-labile factor was increased 105-fold during the last three steps, with a yield of 37% of the activity. One major and several minor bands were visible when the preparation was examined by SDS-polyacrylamide gel electrophoresis with Coomassie blue staining. The major band corresponded to a protein of molecular weight 32,700, and the minor bands corresponded to proteins of molecular weights 62,000 and 67,000. The activity was lost when the heat-labile factor was incubated with 1 mM- N -ethylmaleimide. This inhibition was prevented by preincubating the heat-labile factor with 1 mM-NADH. These observations indicate that the heat-labile factor contains a sulfhydryl group which is essential for activity, and that it is located at or near the binding site for the pyridine nucleotide.     

Oxidation of hydroxylamine to nitrite catalyzed by hydroxylamine oxidoreductase purified fromNitrosomonas europaea

The oxidation of hydroxylamine to nitrite, which had been catalyzed by hydroxylamine oxidoreductase purified fromNitrosomonas europaea, was studied. The enzyme oxidized hydroxylamine almost completely to nitrite under aerobic conditions if sufficient amount of cytochromec or ferricyanide was added and the reaction was performed in phosphate buffer. Even under anaerobic conditions, hydroxylamine was oxidized to nitrite by the enzyme, but nitrite, once formed, disappeared when the reaction was continued for more than several minutes.     

Intramembranous particles on freeze-fractured membrane replica and sulfhydryl groups

Summary The correlated distribution of intramembranous particles and sulfhydryl groups was examined in normal adult rabbit erythrocyte ghosts. Ghosts were treated to exhibit characteristic patterns of particle distribution and sulfhydryl groups were stained with Fast Blue BBN. It was shown that particles and sulfhydryl groups were located in corresponding patterns. The results indicate that the intramembranous particles in the erythrocyte membrane consist predominantly of protein.Supported by grants from the Japanese Government, Nos. 244016 and 337001     

Structure of slow-reacting substance of anaphylaxis (SRS-A)

To elucidate the chemical structure of slow-reacting substance of anaphylaxis from rat (SRS-A^rat), SRS-A^rat were purified by the method of Orange with modification using DEAE-Sephadex A-25 chromatography. Ultraviolet absorption spectrum of purified SRS-A^rat indicated the presence of conjugated triene. Arylsulfatase B degradation products and HCl degradation products were subjected to analysis by a gas chromatography and mass spectrometry and a thin layer chromatography. Products obtained by arylsulfatase B catalysis contained 5,6-dihydroxy-7,9,11,14-eicosatetraenoic acid. HCl degradation products showed the presence of glycine, glutamic acid and cysteic acid. Furthermore, the analysis of anhydrous hydrazine degradation products of SRS-A^rat and of HCl hydrolyzed products of dinitrophenylated SRS-A^rat revealed the presence of glycine at C-terminal and glutamic acid at N-terminal. The study of the substrate specificity of arylsulfatase B against various materials including SRS-A^rat suggested the presence of sulfone in SRS-A^rat. The molecular ion peak of SRS-A^rat sodium salt was observed at m/e 680 in field desorption mass spectrum of SRS-A^rat.On the basis of these data, we identified the structure of SRS-A^rat as [γ-glutamyl-4(5-hydroxy-7,9,11,14-eicosatetraenoic acid-6-yl)-4,4-dioxocysteinyl] glycine.