BINDING OF HEAVY-METALS BY THE CELL-WALLS OF SACCHAROMYCES-CEREVISIAE

The isolated cell walls of the yeast Saccharomyces cerevisiae bound th e heavy metals Cu2+, Cd2+, and Co2+ (0.40, 0.17, and 0.11 mu mol mg(-1 ) metal per wall dry mass). Chemical modification of the isolated cell walls modified their capacity to accumulate Cu2+ cations. The blockin g of amino, carboxyl, or hydroxyl groups reduced the quantity of Cu2accumulated, indicating that they may each play a role in the binding of Cu2+. This in turn indicates that both the protein and the carbohyd rate fractions of the cell walls are involved in heavy metal cation bi nding. Scatchard analysis of the binding of metal cations to both chem ically modified and unmodified isolated cell walls indicates that ther e are different types of binding site.