A comparative study of the effect of various detergents on the structure and function of sarcoplasmic reticulum...

The effects produced by the detergents Triton X-100, sodium dodecylsulphate and sodium cholate on sarcoplasmic reticulum vesicles have been comparatively studied. In all cases, maximal effects are found 5 min after detergent addition. Triton X-100 and SDS are approximately ten times more effective than cholate in protein and phospholipid solubilization. Both Triton X-100 and SDS maintain Ca++ accumulation in SR vesicles at detergent concentrations below 10(-3) M; higher concentrations cause a strong inhibition. On the other hand, cholate produces a gradual inhibition of Ca++ accumulation in the concentration range between 10(-4) M and 2.5 X 10(-2) M. Triton X-100 and SDS produce a gradual solubilization of the specific Ca++-ATPase activity up to a 10(-3) M detergent concentration, above which a strong inactivation occurs, while the enzyme solubilization increases with the presence of cholate in the whole concentration range under study. The different behaviour of sodium cholate, when compared to SDS or Triton X-100, is discussed in relation to the surfactant molecular structures. The possibility of membrane lysis and reassembly in the presence of some detergents is also considered.