Mixed micelle detergent buffer

In Protocol IB, a soluble whole cell extract is produced by lysis in RIPA, a mixed micelle detergent-containing buffer. RIPA buffer results in extraction of proteins without complete denaturation and cellular antigens are maintained in conformations that can be detected by immrmopredpitation (Protocol 14B). How-... 

In Protocol 14C, immunoprecipitation is performed under disruptive conditions in a mixed micelle detergent buffer (RIPA). Most physiological interactions are dissociated imder these stringent conditions, and usually only the antigen protein and veiy tightly-associated proteins are recovered by immunoprecipitation. This method is useful to quantitate levels of pS]methionine labelled protein antigen, and to study synthesis and degradation rates by pulse chase analysis. 

The stability of the non-ionic surfactant, sucrose monolaurate, below and above its CMC has been studied. Below the CMC first-order kinetics are observed for its hydrolysis to lauric acid, but this is not so above the CMC. In buffered systems at a pH when the lauric acid is ionized, the product of hydrolysis appears to form mixed micelles with the sucrose monolaurate, producing negatively charged micelles which appear to protect the ester from attack and thus reduce rates of hydrolysis [155]. Sodium dodecyl sulphate is more stable to hydrolysis in alkaline solutions above its CMC than in acid solutions where the rate of hydrolysis is proportional not only to the hydrogen ion concentration, but also to the concentration of the detergent itself [156]. This agrees with the observation of Kurz [157] that the proton-catalysed rates of hydrolysis of mono-... 

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