A significant increase in the yield of protein extraction by the addit
ion of sulfobetaine-type mild solubilization agents is shown for micro
somal membrane proteins and proteins from lyophilized platelets, with
a maximum increase in yield of up to 100%. These agents are also appli
ed to native isoelectric focusing in immobilized pH gradients. The abs
ence of significant denaturation induced by these solubilizers is show
n for creatine kinase.