Detergent perturbation

Loden, M. and Barany, E., Skin-identical lipids versus petrolatum in the treatment of tape-stripped and detergent-perturbed human skin, Acta Derm. Venereol., 80, 412, 2000. 

Treatment of total human plasma proteins with sodium cholate and subsequent removal resulting in remodeling of the lipoproteins. See Pownall, H.J., Remodeling of human plasma lipoproteins by detergent perturbation. Biochemistry 44, 9714-9722, 2005. 

Since it might be possible that the perturbation of membrane directly stimulated the NADPH-oxidase located on the cell membrane, which is the enzyme for the production of superoxide [24], the possibility was examined by the assay using detergent (Triton X-100) instead of polymers. At 0.001% of Triton X-100, no stimulation of superoxide release from DMSO-differentiated HL-60 cells was observed. At 0.01% of Triton X-100, a... 

When binding of a substrate molecule at an enzyme active site promotes substrate binding at other sites, this is called positive homotropic behavior (one of the allosteric interactions). When this co-operative phenomenon is caused by a compound other than the substrate, the behavior is designated as a positive heterotropic response. Equation (6) explains some of the profile of rate constant vs. detergent concentration. Thus, Piszkiewicz claims that micelle-catalyzed reactions can be conceived as models of allosteric enzymes. A major factor which causes the different kinetic behavior [i.e. (4) vs. (5)] will be the hydrophobic nature of substrate. If a substrate molecule does not perturb the micellar structure extensively, the classical formulation of (4) is derived. On the other hand, the allosteric kinetics of (5) will be found if a hydrophobic substrate molecule can induce micellization. 

Time - resolved spectra of a solid hydrocarbon layer on the surface of an internal reflection element, interacting with an aqueous solution of a nonionic surfactant, can be used to monitor the detergency process. Changes in the intensity and frequency of the CH2 stretching bands, and the appearance of defect bands due to gauche conformers indicate penetration of surfactant into the hydrocaibon layer. Perturbation of the hydrocarbon crystal structure, followed by displacement of solid hydrocaibon from the IRE surface, are important aspects of solid soil removal. Surfactant bath temperature influences detergency through its effects on both the phase behavior of the surfactant solution and its penetration rate into the hydrocaibon layer. 

Orlowski S, Selosse MA, Boudon C, et al. Effects of detergents on P-glycoprotein ATPase activity differences in perturbations of basal and verapamil-dependent activities. Cancer Biochem Biophys 1998 16(l-2) 85-110. 

Solvent-perturbation study of detergent binding AA-peak at 2450 A is not imidazole-based... 

Try AA-peak at 2900 A is connected with catalytic site Classification of tyrosyls by solvent perturbation method A-spectra show different modes of detergent-protein interaction at low and high detergent concentrations... 

It is interesting to note that upon dilution of the apoprotein in 0.05 M sodium dodecyl sulfate at pH 7.3, a loss of the rotatory perturbations in the 250—300 nm range was detected while the iron-conalbumin complex dissociated, as detected by a disappearance of the absorption band at 270 nm, suggesting the detergent affects the protein secondary structure in a way such that the resulting conformation is unfavorable for metal-binding 154). Recent low temperature EPR studies have... 

The kinetic experiments (Figure 32) were carried out with 50 iAf Neutral Red and 40 mg/ml Brij 58 (equivalent to 500(jlM of micellar concentration). At this concentration of detergent, 98% of the indicator is adsorbed. The initial pH of the experiment (7-7.5) ensured that before perturbation the Neutral Red was mostly deprotonated, whereas the proton emitter (2-naphthol, 3,6-disulfonate, pKo = 9-3) was undissociated. Perturbation of the equilibrium by a laser pulse, dissociates Xo molecules of OH, and the relaxation of the system is described by equations (37) and (38). (Direct proton exchange between < >0 and bound indicator can be ignored in this case.) The experimental curve and the simulated function are given in Figure 32. The rate constants of the reaction are listed in Table V. 

Although the presence of buffering moieties on membrane surfaces reduces the apparent diffusion coefficient of a proton, it can enhance the probability that protons in the bulk phase will interact with groups on a membrane surface. This feature is demonstrated by the experiments presented in Figure 3. The measured parameter in these experiments was the protonation of a pH indicator adsorbed to the surface of a micelle made of uncharged detergent (Brij 58). The protons were released in the bulk from a hydrophilic proton emitter, 2-naphthol-3,6-disulfonate. The protons released in the bulk react by a diffusion-controlled reaction with the micelle-bound indicator and lead to a fast protonation phase. The perturbation then relaxes,... 

The adsorption kinetics of a surfactant to a freshly formed surface as well as the viscoelastic behaviour of surface layers have strong impact on foam formation, emulsification, detergency, painting, and other practical applications. The key factor that controls the adsorption kinetics is the diffusion transport of surfactant molecules from the bulk to the surface [184] whereas relaxation or repulsive interactions contribute particularly in the case of adsorption of proteins, ionic surfactants and surfactant mixtures [185-188], At liquid/liquid interface the adsorption kinetics is affected by surfactant transfer across the interface if the surfactant, such as dodecyl dimethyl phosphine oxide [189], is comparably soluble in both liquids. In addition, two-dimensional aggregation in an adsorption layer can happen when the molecular interaction between the adsorbed molecules is sufficiently large. This particular behaviour is intrinsic for synergistic mixtures, such as SDS and dodecanol (cf the theoretical treatment of this system in Chapters 2 and 3). The huge variety of models developed to describe the adsorption kinetics of surfactants and their mixtures, of relaxation processes induced by various types of perturbations, and a number of representative experimental examples is the subject of Chapter 4. 

H. Heerklotz, T. Wieprecht, J. Seelig, Membrane perturbation by the lipopeptide surfactin and detergents as studied by deuterium, J. Phys. Chem. B, 2004, 108, 4909-4915. 

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