Effect of lipid fluidity upon the activity and structure of the 39 kDa porin from Enterobacter cloacae 908S |
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Authors: | R Ghosh R Aggeler |
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Institution: | Pharmaceutical Research Department, F. Hoffmann-La Roche and Co. Ltd, Basel, Switzerland. |
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Abstract: | The 39 kDa porin from Enterobacter cloacae 908S was isolated in a lipopolysaccharide-free form using the non-ionic detergent, octylpentaoxyethylene, and reconstituted into vesicles of dimyristoylphosphatidylcholine (DMPC) and dioleoylphosphatidylcholine (DOPC), respectively. Porin activity, measured by the rate of hydrolysis of the lipid-impermeant beta-lactam cephazoline by entrapped lactamase, could be demonstrated for porin-DMPC but not for porin-DOPC vesicles, and for the former was significantly lower in the gel than in the liquid-crystalline phase. The fluorescence changes are thought to arise from lipid phase-induced structural/dynamic changes of the porin structure. |
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