The biosorption capacity differences of copper cation by yeast Candida utilis cells and isolated cell walls were investigated. The results showed that the metal accumulated by cell walls was usually 50% higher than that by intact cells. This suggested that the cell walls of yeast were the main sites for heavy metal accumulation. Treatments of cell wall with proteinases demonstrated that the copper accumulated by trypsin-treated cell walls was almost the same as that by intact cell walls (95%), while the subtilisin-treated cell walls almost lost the potential of metal accumulateion (only 3%), suggesting that the main sites of copper accumulation in Candida utilis cell walls were trypsin-unsensitive integral proteins. Fig 1, Ref
