Two types of Cd-peptide complexes (Cd-BP1 and Cd-BP2) are induced in the cells of Schizosaccharomyces pombe with addition of Cd ions in a culture medium. The complexes contain Cd and various lengths of peptides (cadystin). One of the complexes, Cd-BP1, also contains acid labile sulphide. The chemical structures of the main component peptides, cadystin A and cadystin B were determined to be γ-L-Glu-L-Cys-γ-L-Glu-L-Cys-γ-L-Glu-L-Cys-Gly, and γ-L-Glu-L-Cys-γ-L-Glu-L-Cys-Gly, respectively. Cadystin syntheses induced with Cd ions in other organisms were studied. Many organisms were found to have the same system with that of Schizosaccharomyces pombe, and to synthesize cadystin by the Cd ion induction. The plant, Silene cucubalus is able to synthesize cadystin molecules on Cd induction. An enzyme which transfers the γ-Glu-Cys moiety of glutathione to an acceptor glutathione was found. The molecular　cloning of the gene was performed, and the enzyme kinetics were studies precisely using the recombinant enzyme. The main components of this tolerance system to Cd ions in the organisms are now described. However, the mechanism of the induction in detail is not sufficiently elucidated yet. The Cd sulphide crystal is a semiconductor. The Cd-sulphide-cadystin complex induced in Schizosaccharomyces pombe by Cd ions was found to be nanoparticles, which consist of the core of Cd sulphide and cadystin molecules coating the core (closed complex). The nanoparticles are stable and monodisperse, and these will be useful materials for the tunable semiconductors with high quality. The high quality semiconductors will be obtained by investigating the culture conditions of Schizosaccharomyces pombe.