The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster in which each Cu atom is bridged by the side chains of two cysteine residues and has terminal N/O ligation.
Kharenko, Olesya A.; Kennedy, David C.; Demeler, Borries; Maroney, Michael J.; and Ogawa, Michael Y., "Cu(i) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-helix Bundle" (2005). Chemistry Faculty Publications. 169.
Journal Of The American Chemical Society