Structural and functional properties of plasma membranes from the filamentous fungus Penicillium chrysogenum

Functional plasma membranes from the filamentous fungus Penicillium chrysogenum have been isolated with the objective of studying transport processes. The isolation procedure consists of three steps, namely homogenization of cells with a Braun MSK homogenizer, followed by Percoll gradient centrifugation and floatation of membranes in a three-step Nycodenz gradient. This method can be applied to strains which differ significantly in morphology and penicillin-production capacity. Plasma membranes were fused with liposomes containing the beef heart mitochondrial cytochrome-c oxidase. In the presence of reduced cytochrome c, the hybrid membranes maintained a high proton motive force that functions as a driving force for the uptake of the amino acids arginine and valine via distinct transport systems.