The addition of Triton X-100 to isolated rabbit intestinal microvilli induced proteolysis of some microvillar proteins. The proteolysis, which was conspicuous in actin, was inhibited by ethylenediamine N, N, N', N'-tetraacetic acid (EDTA) effectively at pH 7.0 but partially at pH 8.6. Phosphoramidon and phenylmethylsulfonyl fluoride showed no inhibitory effect. When microvilli solubilized by Triton X-100 were concentrated, trehalase, a microvillar membrane enzyme, became subject to limited proteolysis, which was also almost completely inhibited by EDTA at pH 7.0. These results show that on solubilization of intestinal microvilli with detergent, care must be taken to avoid induced proteolysis. Most of such proteolysis can be prevented by EDTA at pH 7.0.
