Isolation and Characterization of the Plasma Membrane by Two-Phase Partitioning from the Alkalophilic CyanobacteriumSpirulina platensis

摘要

Partition in aqueous dextran-polyethylene glycol two-phase system was used to isolate the plasma membranes from the alkalophilic cyanobacteriumSpirulina platensis. The upper phase contained a colorless membranes obtained in relatively short time, 3–4 h. This fraction had a different protein profile than that of the thylakoid fraction obtained in the lower phase. It did not contain cytochromec-oxidase activity, but retained characteristic Mg2+-ATPase activity that is sensitive to vanadate, stimulated by K+, and has a pH optimum near 8.5. These data support our assumption that the upper phase of the gradient consist of the plasma membrane ofS. platensi