Induction of cellular efflux by a galactosamine polymer from Neurospora crassa

A cationic polymer of D-galactosamine was isolated from culture filtrates of a colonial temperature-sensitive strain of Neurospora crassa. Adsorption of the polymer to the cell surface initiated immediate efflux of low molecular weight metabolites and subsequent loss of viability. The polymer appeared to bind to those sites on the cell surface that normally bind calcium ions. Chemical analysis of the polymer showed it to be partially N-acetylated. The polymer had an isoelectric point of 8.4. Thirty percent of the D-galactosamine residues contained free amino groups. A rapid assay that has potential application for monitoring the effect of a variety of other membrane-active factors on membrane permeability has been developed.