Metal selective fluorescent peptide probes (dansyl-Cys-X-Gly-His-X-Gly-Glu-NH 2 , X=Pro or Gly) were developed by synthesizing peptides containing His, Cys, and Glu residues with Pro-Gly sequence to stabilize a turn structure and Gly-Gly sequence to adopt a random coil. The probe containing two Gly-Gly sequences exhibited marked selectivity only for Cu 2+ over 13 metal ions including competitive transition and Group I and II metal ions under physiological buffer condition. In contrast, the probe containing double Pro-Gly sequences showed high selectivity for Zn 2+ . The peptide probe containing one Pro-Gly sequence exhibited selectivity for Zn 2+ and Cu 2+ . CD spectra indicated that the secondary structure of the probes played an important role in the selective metal monitoring and a pre-organized secondary structure is not required for the selective detection of Cu 2+ ion, but is required for the detection of Zn 2+ . We investigated and characterized the binding affinity, binding stoichiometry, reversibility, and pH sensitivity of the peptide probes.