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171.
Expression and characterization of human factor IX and factor IX-factor X chimeras in mouse C127 cells 总被引:7,自引:0,他引:7
Human blood clotting factor IX, and two chimeric molecules of factor IX, in which the first epidermal growth factor-like domain or both epidermal growth factor-like domains have been replaced by that of human factor X, have been expressed in mouse C127 cells. The recombinants have been purified using a metal ion-dependent monoclonal antibody specific for residues 1-42 of human factor IX. All recombinant molecules are activated normally by human factor XIa in the presence of calcium ion. Activation of the factor IX recombinants by factor VIIa-tissue factor appears to be normal for the epidermal growth factor-1 exchange but considerably reduced for the construction containing both epidermal growth factor-like domains of factor X. The analysis of gamma-carboxyglutamic acid residues reveals that all of the purified recombinants are almost fully carboxylated. The extent of aspartic acid hydroxylation at residue 64 is 60% for all recombinants. The chimeric molecule with both epidermal growth factor-like domains from factor X has about 4% normal activity in the activated partial thromboplastin time assay. In contrast, the construct containing the first epidermal growth factor-like domain of factor X shows essentially normal clotting activity. Thus, it is unlikely that this domain is involved in a unique interaction with factor VIII. 相似文献
172.
Kuang-Tzu Davis Lin 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1982,227(2):341-348
A column chromatographic analysis of 3-hydroxyproline (3-Hyp), 4-hydroxyproline (4-Hyp), and γ-carboxyglutamic acid (Gla) is described. The analyses of urine and plasma were performed with a JLC-6AH amino acid analyzer. A 0.15 M sodium citrate buffer, pH 2.1, was used for elution. Urinary Gla, 3-Hyp, and 4-Hyp were among the seventeen peaks eluted before asparti acid. Hyp, Gla, glutamine, and asparagine in plasma were separated by elution with 0.2 M sodium citrate buffer, pH 3.25, containing 10% methanol. This single-column procedure achieves the sequential separation and quantitation of Gla, 3-Hyp, and 4-Hyp in urine as well as plasma, and is applicable to the diagnosis of collager, metabolism disorders. 相似文献
173.
The androgen receptor from mouse kidney cytosol has been studied for its nucleic acid binding properties by DNA-cellulose centrifugation assay. The receptor appears to bind to RNA (mRNA, tRNA, rRNA) as well as to DNA. Salt and heat activation of the androgen receptor enhances both DNA and RNA binding. The receptor binds slightly better to denatured DNA than to native DNA. The androgen receptor binds about 2-fold tighter to poly(dG-dC) than to poly (dA-dT). The interaction of the receptor with DNA is not greatly affected by the BrdUrd substitution. The observation that androgen receptor shows a significant affinity to RNA may imply that androgen receptor-RNA interaction could play a role in gene regulation. 相似文献
174.
A simple photolithographic technique has been developed which can be used to produce microscopic grid patterns on glass coverslips. The grid pattern is first photo-reduced onto film, and the resulting photographic negative is then used as a mask. A glass slide or coverslip, coated with a layer of photoresist, is then exposed to tungsten light through the mask. After developing and etching, the grid pattern is transferred permanently onto glass. This simple and rapid procedure allows one to mass-produce very small, high resolution grids which are useful for monitoring individual microinjected cells or chromosomal spreads under the microscope. 相似文献
175.
Substrate specificity and transport properties of the glycerol facilitator of Escherichia coli. 总被引:37,自引:17,他引:20 下载免费PDF全文
The specificity of the glycerol facilitator (glpF) of Escherichia coli was studied with an osmotic method. This transport system allowed the entry of polyols (glycerol and erythritol), pentitols, and hexitols. The analogous sugars were not transported. However, urea, glycine, and DL-glyceraldehyde could use this pathway to enter the cell. The glpF protein allowed the rapid efflux of preequilibrated xylitol. Glycerol surprisingly did not inhibit the uptake of xylitol, and xylitol only slightly reduced the uptake of glycerol. The observation and the insensitivity of the xylitol transport to low temperature suggest that the facilitator behaves as a membrane channel. 相似文献
176.
J S Lin 《Journal of general microbiology》1980,116(1):187-193
Antigenic components at the outer surface membranes of seven serotypes of Mycoplasma hominis were analysed by the mycoplasmacidal reaction and the agglutination during growth reaction. Antibody absorbing capacities of the mycoplasma cells were compared with absorbing capacities of membranes. It was shown that serologically active membrane antigens were mainly heat-labile proteins. No major antigens common to all seven serotypes were detected and each strain had its own specific antigens at the cell surface. Results of analysis indicate that there is a complex antigenic structure exposed in M. hominis and that 7 to 14 cross-reacting antigens may be present at the outer surface in the different serotypes examined. Additional cross-reacting antigens, presumably inner membrane in origin and not exposed at the cell surface, were also demonstrable. 相似文献
177.
178.
Mouse liver Kupffer cells were induced to proliferate and form discrete colonies of mononuclear phagocytes in vitro. These colony-forming cells from the liver are similar to other mononuclear phagocyte colony-forming cells in that they require a colony-stimulating factor present in medium conditioned by L cells for proliferation in vitro. Cells in the colonies were phagocytic and had IgG receptors on the membrane. For this class of colony-forming cells, the D0 value to gamma irradiation in vitro was 108 rads. 相似文献
179.
S. H. Lin 《Bulletin of mathematical biology》1979,41(2):151-162
Diffusion problem with variabale diffusion coefficient in a spherical biological system is investigated. Also included in
this study is the biological reaction of the Michaelis-Menten type. The problem formulated consists of a highly nonlinear
differential equation which, however, can be efficiently solved by the orthogonal collocation method on a digital computer.
The effects of the dimensionless governing parameters on the transient and steady state concentration responses are parametrically
examined for the diffusion system with and without biological reaction. 相似文献
180.
The intermediate scattering function G(K,t) for any polymer model obeying a linear separable Langevin equation can be expressed in terms of the eigenvalues and eigenvectors of its normal coordinate transformation. An algorithm for the extract numerical evaluation of G(K,t) for linear Rouse-Zimm chains in the presence of hydrodynamic interaction has been developed. The computed G(K,t)2 were fit to C(t) = A exp(?t/τA) + B, and apparent diffusion coefficients calculated according to Dapp ≡ 1/(2τAK2). G(K,t)2 was surprisingly well-fit by single-exponential decays, especially at both small and large values of Kb, where K is the scattering vector and b the root-mean-squared subunit extension. Plots of Dapp vs K2 in-variably showed a sigmoidal rise from D0 at K2 = O up to a constant plateau value at large K2b2. Analytical expression for G(K,t), exact in the limit of short times, were obtained for circular Rouse-Zimm chains with and without hydrodynamic interaction, and also for free-draining linear chains, and in addition for the independent-segment-mean-force (ISMF) model. The predicted behaviors for G(K,t) at large Kb (or KRG) was found in all cases to be single-exponential with 1/τ ∝ K2 at large Kb, in agreement with the computational results. A simple procedure for estamating all parameter of the Rouse-Zimm model from a plot of Dapp vs K2 is proposed. Experimental data for both native and pH-denatured calf-thymus DNA in 1.0M Nacl with and without EDTA clearly plateau behavior of Dapp at large values of K, in harmony with the present Rouse-Zimm and ISMF theories, and in sharp contrast to previous predictions based on the Rouse-Zimm model. 相似文献