PubMed · 8901398
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E M De Boer, D P Bruynzeel. Patch tests: evaluation by instrumental methods.. https://doi.org/10.1016/0738-081x(95)00107-q
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The interaction of the nonionic detergent Triton X-100 with supported phosphatidylcholine planar lipid bilayers has been investigated by optically monitoring changes in the bilayer, using the technique of optical waveguide lightmode spectroscopy (OWLS). This technique has several advantages over the methods applied to the problem hitherto, including: high sensitivity; measurement in situ with good time resolution; the fact that the free detergent concentration is well-defined, and the lipid concentration in solution is zero; ease of studying the reversibility of the interaction; and the readiness with which absolute rather than effective amounts of detergent incorporated into the lipid can be determined. The main finding is that as the free Triton concentration increases, the detergent is first incorporated reversibly into the bilayer, then partly but never completely removes lipid, and finally (at or above the cmc) completely solubilizes the bilayer. The behaviour of the lanar supported lipid bilayers is thus similar to that previously reported for lipid vesicles.
The use of enzymes in low water environments permits reactions to occur that are difficult or impossible in aqueous solution. In this manner, proteases can be used to form, rather than hydrolyze, ester and amide linkages. Presumably, the native-like structure of the enzyme must remain intact for catalysis to transpire. However, little is known regarding the integrity of the overall structure of lyophilized proteins suspended in organic media. In this study, the structural changes that occur during the freeze-drying process and those effected by suspension in the organic solvent were examined. Using Fourier-transform infrared spectroscopy, the secondary structure of lyophilized subtilisin BPN' was monitored and correlated to the level of enzymatic activity when suspended in isooctane. In addition, the ability of ionic detergents to stabilize subtilisin BPN' via ion pairing was evaluated. It was found that subtilisin unfolds to some degree during lyophilization, whether it is ion paired or not. Furthermore, there are structural changes observed when the enzyme is placed in isooctane, although the effects are less with ion-paired subtilisin. This higher level of retention of secondary structure results in increased enzymatic activity.
We examined the effect of six types of the nonionic detergent Triton X on the susceptibilities of methicillin-resistant staphylococci to oxacillin. We used five methicillin-resistant Staphylococcus aureus isolates and 17 methicillin-resistant coagulase-negative staphylococci isolates. All strains of S. aureus, S. epidermidis and S. sciuri had enhanced susceptibility to oxacillin following exposure to the types of Triton X having 7-13 polymerized ethylene oxides. These strains were altered from homogeneously resistant to heterogeneously resistant by Triton X-100. Those types of Triton X that affected the resistance level also promoted the release of lipoteichoic acid. These results and those of previous studies suggest that Triton X might act on factors other than the mecA or femA products.