Characterization and physico-chemical properties of human transcortin]

The molecular weight of human transcortin, calculated from the sedimentation coefficient, was found to be 49,500, thus slightly lower than previously reported values. After purification, human transcortin trended to polymerize rapidly, with participation of both non covalent bonds and one disulfide bridge per dimer. The physicochemical parameters, the amino-acid and carbohydrate composition were determined; its stability was studied under different conditions. Preliminary structural studies showed that the N-terminal sequence of the polypeptide chain was: Met-Asp-Pro-Asn-Ala-Ala-Tyr-Val and that the C-terminal amino acid was leucine.     

Relationship between the "phospholipid effect" and calcium in the thyroid. I. - Effects of calcium ions, E.G.T.A., ionophore A 23187, verapamil and chlorpromazine on resting and stimulate thyroid slices.

The "phospholipid effect" which is the enhanced turnover of the phosphorylinositol group of phosphatidylinositol (PI) occurs in the thyroid of response to thyreostimulin (TSH). The possibility that Ca2+ ions are involved in this stimulation has been investigated with pig thyroid slices. Experiments performed in media without Ca2+ or containing E.G.T.A. (2 mM), indicate that it is not the extracellular Ca2+ which is implied, but rather the intracellular Ca2+. The ionophore A23187 (6.10(-6) M) increases the specific radioactivity of the acid soluble precursors, but has also a specific effect on the PI turnover, which is additive with the effect of a high concentration of TSH (50 mU/ml). Washing and loading of slices with various Ca2+ concentrations show that 0.9 mM restores the TSH phospholipid effect. Verapamil (10(-3) M) and Chlorpromazine (10(-3) M) redirect glycerolipid metabolism by increasing PI and phosphatidic acid (PA) synthesis at the expense of other glycerolipids, as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). These results suggest that the "phospholipid effect" is not a result of Ca2+ entry into the thyroid cells. On the contrary, it seems that this increased turnover of PI in "long term" incubations (3 hr). An additive and acute effect of TSH effect is more pronounced when Ca2+ movements     

Neutral calcium dependent proteinase from rabbit skeletal muscle: activity on myofibrillar proteins

Experiments have been carried out to explore the proteolytic cleavage of rabbit skeletal myofibrils by a calcium dependent neutral proteinase (CaANP). Polyacrylamide gel elctrophoresis on great slabs showed the ability of CaANP to degrade myofibrils more readily than supposed. Besides the hydrolysis of troponin T and the apparition of degradation product of 30,000 molecular weight, the activity of this enzyme is obvious too on some components of the M-line and on heavy subunits of tropomyosin as well as on three unidentified proteic fractions. The variety of the degradation products which appear suggest that the specificity of CaANP is not as selective as presumed. The participation of this proteinase in the postmorten evolution of muscle and its intervention in the turnover of myofibrillar proteins is discussed.     

Purification and study of some properties of a collagenase produced by Empedobacter collagenolyticum

A collagenase from Empedobacter collagenolyticum was extracted from the culture medium of the bacteria. The complete purification of the enzyme was achieved by successive ammonium sulfate precipitation. Sephadex G 200 gel filtration and DEAE cellulose chromatography. This collagenase is active on insoluble collagen, and on the synthetic peptide Pz-Pro-Leu-Gly-Pro-D-Arg. Its optimum activity was at 30 degrees C and at pH 7.6. A strong inhibition was observed with chelating agents such as O-phenanthroline and EDTA. Among the cations tested to restore the activity, only Ca2+ has a measurable effect. Heavy metals, Pb, Hg, Cd, Cu, Fe, Co, strongly inhibit the enzyme activity. Zn2+ is also highly inhibitory; 10 microM ZnCl2 completely inhibits the collagenase. p CMB, iodoacetate have little effect on the collagenase. This new collagenase ressembles by most of its properties the already known bacterial collagenases.     

A method to quantify at late imaging a release rate of 18F-FDG in tissues

This theoretical work shows that the rate constant for the (18)F-FDG release in tissues can be assessed without needing any arterial blood sampling. The method requires that the clearance of (18)F-FDG from plasma has occurred, whereas (18)F-FDG is still present in the tissue. This condition can be met dating from 3 h after (18)F-FDG injection, when hydration and/or phlorizin injection are applied after the routine static acquisition. The release rate constant can be obtained from a graphical analysis performed at the later decreasing phase of the tissue tracer activity. A two-compartment and a three-compartment model are developed, both in accordance with one another. To cite this article: E. Laffon et al., C. R. Biologies 328 (2005).     

Molecular structure for microbial polysaccharides: conformation of the Klebsiella serotype K9 capsular polysaccharide

Fibre type X-ray diffraction patterns have been obtained from oriented, semicrystalline films prepared from the sodium salt form of the bacterial capsular polysaccharide of Klebsiella serotype K9. The molecule has a pentasaccharide repeating sequence, with four neutral residues in the backbone and a glucoronic acid side chain. A novel feature of the molecule is the incorporation of α-l-rhamnose residues, one 1,2 linked and two 1,3 linked in the backbone. Analysis of the X-ray diffraction results indicate an extended three-fold helical conformation with an axially projected chemical repeat of 1.377 nm. Both left and right handed helices have been examined using linked atom least squares techniques to optimize the stereochemistry while simultaneously meeting the observed helical parameters.     

色木槭的变异式样及其分类学

色木槭(Aeer mono Maxim.)是分布于亚洲东部的一个变异极大的种。本文报道了7个亚种:色木槭(原亚种)(subsp.mono);海岛色木槭(亚种)(subsp.marmoraturn(Nichols.)T.Z.Hsu);毛萼色木槭(亚种)(subsp.glabrum(Levl.et Vant.)T.Z.Hsu);里光色木槭(亚种)(subsp.trichobasis(Nakai)T.Z.Hsu);金沙色木槭(亚种)(subsp.tricuspis(Rehd.)T.Z.Hsu);弯翅色木槭(亚种)(subsp.incurvaturn(Fang et P.L.Chiu)T.Z.Hsu);粉绿色木槭(亚种)(subsp.glaucum(Koidz.)T.Z.Hsu),讨论了其变异式样和地理分布。     

Isolation of tumor disturbing factor on the proliferation of tumor cells in human serum

The classified sediment with ethanol from sera of nude mice and humans showed a disturbing effect on L1210 cells in vitro and a lifesaving effect on L1210 cell-bearing mice in vivo. This factor was purified more than 2300-fold to a specific activity of approximately 1 X 10(5) U/mg by ethanol classified precipitation, Sephadex G-200 gel filtration, DEAE cellulose ion exchange chromatography with Nacl and pH gradient aqueous solution, and preparative polyacrylamide gel electrophoresis.