Complexes in vitro

Table 3. Equilibrium Dissociation Constants for Drug—Receptor Complexes In Vitro...

The major lipid-soluble antioxidant primarily associated with lipid membranes is a-tocopherol (vitamin E). Circulating a-tocopherol is carried by chylomicrons, LDL and HDL and also has extracellular antioxidant capacities. As a chain-breaking antioxidant, it short circuits the propagation phase of lipid peroxidation because the peroxyl radical will react with a-tocopherol more rapidly than a polyunsaturated ffitty acid (Burton and Traber, 1990). The resulting a-tocopheryl radical reacts with a second peroxyl radical to form an inactive, nonradical complex. In vitro, ascorbate regenerates the tocopheryl radical into its native non-radical form (Burton and Traber, 1990). 

Strausfeld, U Labbe, J. C., Fesquet, D., Cavadore, J. C., Picard, A., Sadhu, K., Russell, P., and Doree, M. (1991). Dephosphorylation and activation of a p34c[Pg.51]

Lindh, J.G., Connolly, B., McGhie, D.L. and Smith, D.F. (1998) Identification of a developmentally regulated Trichinella spiralis protein that inhibits MyoD-specific protein DNA complexes in vitro. Molecular and Biochemical Parasitology 92,163-175. 

Bao A, Goins B, Klipper R, Negrete G, Mahindaratne M, Phillips WT. A novel liposome radiolabeling method using Tc-SNS/S complexes in vitro and in vivo evaluation. J Pharm Sci 2003 92 1893. 

Pauli, T.T., Carey, M., and Johnson, R.C. (1996) Yeast HMG proteins NHP6A/B potentiate promoter-specific transcriptional activation in vivo and assembly of preinitiation complexes in vitro. Genes Dev. 10, 2769-2781. 

Eastman, S.J., Tousignant, J.D.,Lukason, M.J., Chu, Q., Cheng, S.H. andScheule, R.K. (1998) Aerosolization of cationic lipid pDNA complexes In vitro optimization of nebulizer parameters for human clinical studies. Hum. Gene Then, 9, 43-52. 

HAP1A) (Tang et al., 2003). In biochemical experiments, we demonstrated the formation of InsP3Rl-HAPlA-Htt ternary complex in vitro and in vivo (Tang et al., 2003). 

Motivated by its important role in gene delivery, we have studied the effect of cholesterol (chol) and several analogs on the transfection efficiency of lamellar CL-DNA complexes in vitro [27]. As evident from the results on DOPC/DOTAP and DOPE/DOTAP vectors, the nature of the neutral lipid component is an important parameter that is worth further exploration. Conveniently, a number of neutral lipids are commercially available. In addition, modifying the neutral lipid component has the potential to improve TE in a regime (at low aM) where DNA dissociation from the complex in the cytosol is not yet a barrier to transfection. 

Twaites BR, CdlH A, Cunliffe D et al (2004) Thermo and pH responsive polymers as gene delivery vectors effect of polymer architecture on DNA complexation in vitro. J Control Release 97 551-566... 

Saponins appear to lower plasma LDL cholesterol concentration by interfering with cholesterol absorption. Studies in rats and monkeys fed naturally occurring saponins exhibited significant reductions in cholesterol absorption efficiency and an increase in fecal cholesterol excretion (Malinow et al., 1981 Nakamura et al., 1999 Sidhu et al., 1987). Decreased bile acid absorption and increased excretion has also been reported in animals fed saponins (Malinow et al., 1981 Nakamura et al., 1999 Stark and Madar, 1993). One possible mechanism of action for decreased cholesterol absorption is the ability of saponins to form insoluble complexes with cholesterol (Gestetner et al., 1972 Malinow et al., 1977). In an effort to isolate the specific properties of saponins, Malinow (1985) prepared a variety of synthetic saponins in which the complex carbohydrate moieties of native plant saponins were replaced with simplified carbohydrates such as glucose or cellobiose. One of these synthetic saponins, tiqueside (Pfizer, Inc.), can effectively precipitate cholesterol from micelle solutions in vitro and inhibit cholesterol absorption in a variety of animals (Harwood et al., 1993) and in humans (Harris et al., 1997). But despite ample data showing the formation of a saponin/cholesterol complex in vitro, there is essentially no definitive evidence that complexation occurs in the intestinal lumen (Morehouse et al., 1999). 

In conclusion, we have designed a synthetic vesicular DNA carrier that physically and functionally mimics an enveloped virus particle. To achieve an acceptable degree of encapsulation within the vesicle, we use a process that is essentially inverse to the preparation of cationic lipid-DNA complexes. A suitable DNA condensing agent is introduced that, at a certain critical concentration, conveys a weak net cationic charge to the condensed DNA that then interacts spontaneously with a liposome containing one or more anionic components. These DNA formulations behave distinctly different from classic cationic liposome DNA complexes in vitro in as much as they have been shown to be nontoxic, to display a traditional linear dose response, and to be serum-insensitive. 

Recent studies show that nucleosome/antinucleosome immune complexes contribute more to lupus nephritis. Serum anti-dsDNA reactivity is always associated with antinucleosome reactivity (A18, B26, B28, B29, C9). Even the highly purified monoclonal and polyclonal anti-dsDNA antibodies selected by affinity chromatography bind to isolated dsDNA and also to nucleosomes (C9, L23). Hybridoma-secreting anti-DNA can also form immune complexes in vitro with nucleosomes released from dying hybridomas in culture (F9). Finally, the binding of an anti-DNA antibody to a nucleosome may render the immune complex more positive and thereby make it more prone to bind to the GBM (T2). 

Efforts to test hypothesis two by biochemical reconstitution of a functional desaturase complex in vitro proved technically difficult and failed to provide a reproducible assay for functional expression of cloned lepidopteran desaturase sequences. In contrast, an in vivo expression system consisting of the yeast olel mutant and YEpOLEX plasmid confirmed hypothesis two and provided a technically facile and robust assay for determining the functional identities of many moth desaturase-encoding cDNAs. Particularly desirable features of this... 

Scharfstein, J., Correa, E. B., Gallo, G. R., and Nussenzweig, V., Human C4-binding protein. Association with immune complexes in vitro and in vivo. J. Clin. Invest. 63, 437-442 (1979). 

Cesareo E, Parker LJ, Pedersen JZ, Nuccetelli M, Mazzetti AP, Pastore A, Federici G, Caccuri AM, Ricci G, Adams JJ, Parker MW, Lo Bello M (2005) Nitrosylation of human glutathione transferase Pl-1 with dinitrosyl diglutathionyl iron complex in vitro and in vivo. J Biol Chem 280 42172 12180... 

Most anaerobically functioning mitochondria use endogenously produced fumarate as a terminal electron-acceptor (see before) and thus contain a FRD as the final respiratory chain complex (Behm 1991). The reduction of fumarate is the reversal of succinate oxidation, a Krebs cycle reaction catalysed by succinate dehydrogenase (SDH), also known as complex II of the electron-transport chain (Fig. 5.3). The interconversion of succinate and fumarate is readily reversible by FRD and SDH complexes in vitro. However, under standard conditions in the cell, oxidation and reduction reactions preferentially occur when electrons are transferred to an acceptor with a higher standard redox potential therefore, electrons derived from the oxidation of succinate to fumarate (E° = + 30 mV) are transferred by SDH to ubiquinone,... 

Many drugs undergo complex in vitro drug degradations and biotransformations in the body (i.e., pharmacokinetics). The approaches to solve the rate equations described so far (i.e., analytical method) cannot handle complex rate processes without some difficulty. The Laplace transform method is a simple method for solving ordinary linear differential equations. Although the Laplace transform method has been used for more complex applications in physics, engineering, and other research areas, here it will be applied to ordinary differential equations of first-order rate processes. 

Plants contain signiFcant concentrations of polysaccharides of which the potentially negatively charged oxygen functions can bind cations electrostatically or chelate them via polyhydroxy groups [89]. Particular attention was attracted by a structurally complex pectic polysaccharide rhamnogalacturonan-II (RG-II) [90]. This ubiquitous component of primary plant cell walls forms dimers cross-linked by 1 2 borate diol esters (dRG-II) that were found to complex in vitro sped be divalent cations and the majority of Ba, Pb, Sr, and rare earth elements (REEs) in fruit and vegetables [45, 91]. 

Reactions of free radicals with molecules of biological interest have been the focus of attention of radiation chemists and biologists for decades (for a review of the chemical aspects of these reactions, see ref. [17]). More recently, other means of producing free radicals have been employed to study more complex in vitro systems [18]. These methods include ... 

Enzymatic degradation of amylose is inhibited by complexation with lipids.848-894 Decreased digestibility of complexes in vitro and in vivo have been observed, and such results suggest the feasibility of enzyme-assay... 

Bermudez VP, Lindsey-Boltz LA, Cesare AJ, Maniwa Y, Griffith JD, Hurwitz J, Sancar A. Loading of the human 9-1-1 checkpoint complex onto DNA by the checkpoint clamp loader hRadl7-replication factor C complex in vitro. Proc. Natl. Acad. Sci. U.S.A. 2003 100(4) 1633-1638. 

The methyl-Coenzyme M reductase (MR) reaction, whereby the methyl group of methyl-CoM is reduced by two electrons to form methane, is given in Reaction (21). It is likely catalyzed by one enzyme in vivo, but may be physically associated with one or more enzymes in what has been termed a methanoreductosome. The reaction involves three coenzymes methyl-CoM, F430, and HSHTP. The picture is more complex in vitro, since various activation and reduction components have been used in attempts to obtain high specific activity enzyme preparations, although even in vitro the reaction clearly proceeds by MR catalysis alone. The MR is also known as Component C [127,128,173,175,386,387]. 

J. P. Gratton, J. Fontana, D. S. O Connor, G. Garcia-Cardena, T. J. McCabe and W. C. Sessa, Reconstitution of an endothelial nitric-oxide synthase (eNOS), hsp90, and caveolin-1 complex in vitro. Evidence that hsp90 facilitates calmodulin stimulated displacement of eNOS from caveolin-1. J Biol Chem 275,22268-22272 (2000). 

The synthesis of the new epicuticle and exocuticle commences during premoult, requiring the resorption of the old exoskeleton across its surface. In fact, high rates of calcium flux occur across the pre-exuvial cuticle-epidermis complex in vitro (R. Roer, personal communication). The exocuticle is not mineralized until after moult and then it is calcified simultaneously with the formation and mineralization of the endocuticle. Thus, the exocuticle exists before it is mineralized but the endocuticle is secreted and calcified simultaneously (Travis, 1965). 

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