2D‐isolation of pure plasma and thylakoid membranes from the cyanobacteriumSynechocystissp. PCC 6803

Abstract
Aqueous polymer two‐phase partitioning in combination with sucrose density centrifugation offered, for the first time, a 2D‐separation method for the isolation of pure plasma and thylakoid membranes from the cyanobacteriumSynechocystis6803 without any cross‐contaminations. The purity of the membrane fractions was verified by immunoblot analysis using antibodies against membrane‐specific marker proteins. As an initiation of a proteomics project, two prominent proteins, which were observed only in the plasma membrane (Slr1513, a hypothetical protein, and HofG, a general secretion pathway protein), or in the thylakoid membrane (PsaE, a photosystem I protein, and NdhH, a subunit of NADH dehydrogenase), were identified.