Isolation of Cyanobacterial Plasma Membranes

Abstract

This chapter focuses on the isolation of cyanobacterial plasma membranes. Cyanobacteria are classified as gram-negative bacteria, in which the cell envelope is composed of outer and inner (plasma or cytoplasmic) membranes with a peptidoglycan layer in between. In the cytoplasm are the thylakoid membranes, which are the site of light capturing, electron transport, and ATP synthesis. The thylakoid membranes represent most of the total cellular membranes, and this situation made it difficult for a long time to purify plasma membranes from the cyanobacteria. Subsequently developed methods to isolate plasma membranes are essentially the same as their method, although some modifications are employed such as using a French pressure cell for disruption of the cells and flotation centrifugation for isolation of plasma membranes. Plasma membranes thus prepared can be identified by electron microscopy and also by labeling the intact cells prior to disruption with a membrane-impermeant protein marker such as diazobenzene [35S]sulfonate. © 1988, Elsevier Inc. All rights reserved.