Proteins displacement

Based on experimental evidence from AFM, the physical mechanism of orogenic5 displacement was proposed (Mackie et al., 1999b, 2000, 2003). A crucial aspect of the mechanism is that the surfactant domains exert a lateral surface pressure which compresses the protein layer. The AFM data obtained by Mackie and co-workers (1999b) provided direct visual evidence, for the first time, of a gel-like protein network at the air-water interface, as well as a structural explanation of protein displacement by small-molecule surfactant. In essence, the process of orogenic5 displacement is assumed to involve three stages ... 

Dickinson, E., Tanai, S. (1992). Protein displacement from the emulsion droplet surface by oil-soluble and water-soluble surfactants. Journal of Agricultural and Food Chemistry, 40, 179-183. 

E, and K which must be assembled in the correct sequence. A chaperonin PapD is also required as is an "usher protein," PapC,50 and also the disulfide exchange protein DsbA (Chapter 10). DsbA helps PapD to form the correct disulfide bridges as it folds and PapD binds and protects the various pilus subunits as they accumulate in the periplasmic space of the host. The usher protein displaces the chaperonin PapD and "escorts" the subunits into the membrane where the extrusion occurs.50 55... 

Sandson NB, Marcucci C, Bourke DL, Smith-Lamacchica R. An interaction between aspirin and valproate the relevance of plasma protein displacement dmg-dmg-interactions. Am JPsychiatry 2006 163 1891-6. 

Finally, free drug levels may be affected by interaction with other medications, which may cause displacement of a drug off the protein. Considering that the elderly are taking more medications, they are more likely to experience protein-displacement drug interactions. However, protein-displacement interactions are not considered as clinically significant as metabolism interactions. 

Table 4 In vivo drug interactions caused by protein displacement...

Apoptosis is caused by the release or activation of one or more BH3 domain-only proteins (Fig. 13.9c, step 1). These initiating B 13-only proteins bind to a cytosolic heterodimer containing a Bcl-2 protein (step 2) and displace a previously bound BH3-only protein, Bid, BIM or PUMA (step 3). In the case of Bid, dissociation from a partner such as Bcl-2 may be mediated by proteolysis of the Bid N-terminal 60 amino acid residues, creating truncated Bid (tBid), which activates an effector protein. The BH3-only proteins are therefore activators of apoptosis that displace effector proteins (BAK or BAX) from a non-Bcl-2 partner on the cytosolic surface of mitochondria and endoplasmic reticulum (step 4). For example, BAK is attached to an outer mitochondrial membrane channel protein in a healthy cell. An activating BH3-only protein displaces BAK, which then self-aggregates into homodimers that burrow a hole in the mitochondrial or endoplasmic reticular membrane, releasing the contents (step 5). 

From a systematic study focused on fhe tt-A isofherm of protein-LMWE mixed monolayers (including fhe application of fhe additivity rule on miscibility and the quantification of inferacfions between monolayer components by excess free energy ( if has been concluded that, at a macroscopic level, these compounds form a pracfically immiscible monolayer at the air-water interface, af tt < Tlf At higher tt the collapsed protein is displaced from the interface by LMWE (monoglycerides, phospholipids, etc.). The existence of low profein interactions in disordered proteins ((3-casein and caseinate) facilitates the protein displacement by LMWE from fhe air-water interface. However, the lower surface acfivify of unsafurafed-LMWE explains the fact that this lipid has a lower capacity than saturated-LMWE for protein displacement. 

The reasons for these behaviors may be associated again with the immiscibility between protein and LMWE at the air-water interface and to the protein displacement by the LMWE at surface pressures higher than that for protein collapse. 

Gunning, P.A., Mackie, A.R., Gunning, A.R, Wilde, P.J., Woodward, N.C., and Morris, V.J. The effect of surfactant t)rpe on protein displacement from the air-water interface. Food Hydrocolloids, 18, 509, 2004b. 

Various (e.g., interaction of an extraneous SM with fixed protein displaces an SM-reporter complex, resulting in reporter signal drop)... 

Home built (ATR) 50 ng mL Not available D1 protein, displacement Buffer [27]... 

Figure 8 Schematic illustration of four different adsorption/displacement models proposed by Wahlgren and Amebrant [63] for protein and surfactant adsorption to solid surfaces. The three diagrams for each model show protein adsorption, surfactant addition, and state after rinsing. Figure A represents the case where surfactant binds to the protein and the protein-surfactant complex desorbs. Figure B represents protein displacement by the surfactant. Figure C represents reversible adsorption of the surfactant by the protein. Figure D represents reversible adsorption by the surfactant resulting in partial desorption of the protein. The figures relate to a hydrophilic surface at a hydrophobic surface the orientation of the surfactant molecules with respect to the surface will be different. (Reproduced from [63] with permission from Academic Press.)...

Few reports of therapeutically significant interactions of oxicams with other drugs have appeared. Concurrent administration of aspirin has been shown to reduce piroxicam plasma levels by approximately 20%, whereas the anticoagulant effect of acenocoumarin is potentiated, presumably as a result of plasma protein displacement. 

The state of equilibrium in ion exchange chromatography is currently described by stoichiometric models where the solute, for example a protein, displaces a stoichiometric number of salt ions bound on the ion exchanger. A basic concept is the stoichiometric displacement model developed by Kopaciewicz et al. (1983). For monovalent counterions the reaction is described as follows ... 

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