Heterogeneity of Membrane Vesicles from Escherichia coli and Their Subfractionation with Antibody to ATPase

Abstract

The energy-transducing, Mg-Ca activated ATPase (ATP phosphohydrolase, EC 3.6.1.3) of E. coli is located on the inner surface of the cytoplasmic membrane. Antibody to purified ATPase has now been used to demonstrate that membrane vesicles as ordinarily prepared by the lysozyme-EDTA method consist of two distinct populations. About half the vesicles are everted, and thus readily agglutinated by antibody to ATPase, while half are right-side out. NADH oxidase (reduced NAD:O(2) oxidoreductase EC 1.6.99.3) activity is associated almost entirely with everted vesicles, while the ability to concentrate proline is a property of the right-side out vesicles. The results explain the failure of previous workers to observe the energization of membrane vesicles by oxidation of NADH.